diff --git a/src/029-concurrent-goroutines/concurrent-goroutines.go b/src/029-concurrent-goroutines/concurrent-goroutines.go
index 28d05a5..9b3d264 100644
--- a/src/029-concurrent-goroutines/concurrent-goroutines.go
+++ b/src/029-concurrent-goroutines/concurrent-goroutines.go
@@ -9,7 +9,9 @@ import "fmt"
 func f(n int) {
     for i := 0; i < 10; i++ {
         fmt.Println(n, ":", i)
-        time.Sleep(time.Millisecond * time.Duration(rand.Intn(150)))
+        breakTime := time.Duration(rand.Intn(150)))
+        time.Sleep(time.Millisecond * breakTime)
+            
     }
 }
 
diff --git a/src/036-scatter-gather/081-scatter-gather.go b/src/036-scatter-gather/081-scatter-gather.go
index 6b814d8..af00b49 100644
--- a/src/036-scatter-gather/081-scatter-gather.go
+++ b/src/036-scatter-gather/081-scatter-gather.go
@@ -14,8 +14,8 @@ func main() {
         n := i
         wait.Add(1)
         go func() {
-            opTime := rand.Intn(2000)
-            time.Sleep(time.Duration(opTime) * time.Millisecond)
+            opTime := time.Duration(rand.Intn(2000))
+            time.Sleep(opTime * time.Millisecond)
             fmt.Println(n)
             times[n] = opTime
             wait.Done()
diff --git a/src/043-state-goroutine/state-goroutine.go b/src/043-state-goroutine/state-goroutine.go
index 1069873..39c1ade 100644
--- a/src/043-state-goroutine/state-goroutine.go
+++ b/src/043-state-goroutine/state-goroutine.go
@@ -31,13 +31,13 @@ func randVal() int {
     return rand.Intn(100)
 }
 
-func manageState(reads chan *readOp, writes chan *writeOp) {
+func manageState(rs chan *readOp, ws chan *writeOp) {
     data := make(map[int]int)
     for {
         select {
-        case read := <-reads:
+        case read := <-rs:
             read.resp <- data[read.key]
-        case write := <-writes:
+        case write := <-ws:
             data[write.key] = write.val
             write.resp <- true
         }
@@ -63,7 +63,9 @@ func generateWrites(writes chan *writeOp) {
     for {
         key := randKey()
         val := randVal()
-        write := &writeOp{key: key, val: val, resp: make(chan bool)}
+        write := &writeOp{key: key,
+                          val: val,
+                          resp: make(chan bool)}
         writes <- write
         <-write.resp
         atomic.AddInt64(&opCount, 1)
diff --git a/src/050-regexs/regexs.go b/src/050-regexs/regexs.go
index 29c014b..5204f40 100644
--- a/src/050-regexs/regexs.go
+++ b/src/050-regexs/regexs.go
@@ -1,4 +1,4 @@
-// Regexs
+// ## Regexs
 
 package main
 
@@ -18,3 +18,4 @@ func main() {
 
 // todo: more
 // todo: gsub with regexp
+// todo: rename to "Regular Expressions"
diff --git a/src/051-bytes/bytes.go b/src/051-bytes/bytes.go
index 5e337e9..bac0bd4 100644
--- a/src/051-bytes/bytes.go
+++ b/src/051-bytes/bytes.go
@@ -6,7 +6,7 @@ import "fmt"
 
 func main() {
     arr := []byte("some bytes")
-    str := string([]byte{'a', ' ', 's', 't', 'r', 'i', 'n', 'g'})
+    str := string([]byte{'a',' ','s','t','r','i','n','g'})
     fmt.Println(arr)
     fmt.Println(str)
 }
diff --git a/src/052-json/json.go b/src/052-json/json.go
index 1cdf6d7..d085067 100644
--- a/src/052-json/json.go
+++ b/src/052-json/json.go
@@ -1,4 +1,4 @@
-// JSON
+// ## JSON
 
 package main
 
@@ -7,23 +7,25 @@ import "fmt"
 
 func main() {
     // data to bytes/string
-    bol, _ := json.Marshal(true)
-    fmt.Println(string(bol))
+    bolB, _ := json.Marshal(true)
+    fmt.Println(string(bolB))
 
-    num, _ := json.Marshal(1)
-    fmt.Println(string(num))
+    numB, _ := json.Marshal(1)
+    fmt.Println(string(numB))
 
-    str, _ := json.Marshal("gopher")
-    fmt.Println(string(str))
+    strB, _ := json.Marshal("gopher")
+    fmt.Println(string(strB))
 
-    arr, _ := json.Marshal([]string{"apple", "peach", "pear"})
-    fmt.Println(string(arr))
+    arrD := []string{"apple", "peach", "pear"}
+    arrB, _ := json.Marshal(arrD)
+    fmt.Println(string(arrB))
 
-    hsh, _ := json.Marshal(map[string]int{"apple": 5, "lettuce": 7})
-    fmt.Println(string(hsh))
+    hshD := map[string]int{"apple": 5, "lettuce": 7}
+    hshB, _ := json.Marshal(hshD)
+    fmt.Println(string(hshB))
 
     // string to data
-    byt := []byte(`{"Name":"Wednesday","Age":6,"Parents":["Gomez","Morticia"]}`)
+    byt := []byte(`{"num":6.0,"strs":["a","b"]}`)
     var dat map[string]interface{}
     err := json.Unmarshal(byt, &dat)
     if err != nil {
@@ -31,9 +33,9 @@ func main() {
     }
     fmt.Println(dat)
 
-    name := dat["Name"].(string)
-    fmt.Println(name)
+    num := dat["num"].(float64)
+    fmt.Println(num)
 
-    parents := dat["Parents"].([]interface{})
-    fmt.Println(parents)
+    strs := dat["strs"].([]interface{})
+    fmt.Println(strs)
 }
diff --git a/src/053-time/time.go b/src/053-time/time.go
index 095d80c..ad52d34 100644
--- a/src/053-time/time.go
+++ b/src/053-time/time.go
@@ -9,7 +9,8 @@ func main() {
     now := time.Now()
     fmt.Println(now)
 
-    then := time.Date(2009, 11, 17, 20, 34, 58, 651387237, time.UTC)
+    then := time.Date(
+        2009, 11, 17, 20, 34, 58, 651387237, time.UTC)
     fmt.Println(then)
 
     diff := now.Sub(then)
diff --git a/src/058-urls/urls.go b/src/058-urls/urls.go
index 813b541..6fde08c 100644
--- a/src/058-urls/urls.go
+++ b/src/058-urls/urls.go
@@ -7,7 +7,8 @@ import "net/url"
 import "strings"
 
 func main() {
-    u, err := url.Parse("postgres://user:pass@host.com:5432/path?k=v#frag")
+    s := "postgres://user:pass@host.com:5432/path?k=v#frag"
+    u, err := url.Parse(s)
     if err != nil {
         panic(err)
     }
diff --git a/src/060-base64-encoding/base64-encoding.go b/src/060-base64-encoding/base64-encoding.go
index 0ce3396..f7f7679 100644
--- a/src/060-base64-encoding/base64-encoding.go
+++ b/src/060-base64-encoding/base64-encoding.go
@@ -10,15 +10,15 @@ func main() {
     fmt.Println()
 
     // Standard base64 encoding/decoding.
-    stdEnc := base64.StdEncoding.EncodeToString([]byte(data))
-    fmt.Println(stdEnc)
-    stdDec, _ := base64.StdEncoding.DecodeString(stdEnc)
-    fmt.Println(string(stdDec))
+    sEnc := base64.StdEncoding.EncodeToString([]byte(data))
+    fmt.Println(sEnc)
+    sDec, _ := base64.StdEncoding.DecodeString(sEnc)
+    fmt.Println(string(sDec))
     fmt.Println()
 
     // URL base64 encoding/decoding.
-    urlEnc := base64.URLEncoding.EncodeToString([]byte(data))
-    fmt.Println(urlEnc)
-    urlDec, _ := base64.URLEncoding.DecodeString(urlEnc)
-    fmt.Println(string(urlDec))
+    uEnc := base64.URLEncoding.EncodeToString([]byte(data))
+    fmt.Println(uEnc)
+    uDec, _ := base64.URLEncoding.DecodeString(uEnc)
+    fmt.Println(string(uDec))
 }
diff --git a/src/067-spawning-processes/spawning-processes.sh b/src/067-spawning-processes/spawning-processes.sh
index e0ca5ba..62df9ce 100644
--- a/src/067-spawning-processes/spawning-processes.sh
+++ b/src/067-spawning-processes/spawning-processes.sh
@@ -1,6 +1 @@
 $ go run spawning-processes.go 
-Files:
-total 8
-drwxr-xr-x    3 mmcgrana  staff   102 Sep 23 11:35 .
-drwxr-xr-x  101 mmcgrana  staff  3434 Sep 23 11:25 ..
--rw-r--r--@   1 mmcgrana  staff   241 Sep 23 11:37 spawning-processes.go
diff --git a/src/068-execing-processes/execing-processes.go b/src/068-execing-processes/execing-processes.go
index 1603b31..461d502 100644
--- a/src/068-execing-processes/execing-processes.go
+++ b/src/068-execing-processes/execing-processes.go
@@ -11,7 +11,9 @@ func main() {
     if lookErr != nil {
         panic(lookErr)
     }
-    execErr := syscall.Exec(binary, []string{"-a", "-l", "-h"}, os.Environ())
+    args := []string{"-a", "-l", "-h"}
+    env := os.Environ()
+    execErr := syscall.Exec(binary, args, env)
     if execErr != nil {
         panic(execErr)
     }
diff --git a/src/072-https-client/https-client.go b/src/072-https-client/https-client.go
index 7b58a24..98dbdf2 100644
--- a/src/072-https-client/https-client.go
+++ b/src/072-https-client/https-client.go
@@ -8,10 +8,9 @@ import "io/ioutil"
 import "fmt"
 
 func main() {
-    tr := &http.Transport{
-        TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
-    }
-    client := &http.Client{Transport: tr}
+    conf := &tls.Config{InsecureSkipVerify: true}
+    trans := &http.Transport{TLSClientConfig: conf}
+    client := &http.Client{Transport: trans}
     resp, err := client.Get("https://127.0.0.1:5000/")
     if err != nil {
         panic(err)
diff --git a/src/073-redis/redis.go b/src/073-redis/redis.go
index da15664..498bd51 100644
--- a/src/073-redis/redis.go
+++ b/src/073-redis/redis.go
@@ -35,26 +35,26 @@ func main() {
     fmt.Println(mgetRep)
 
     // multi calls
-    mcallRep := client.MultiCall(func(mc *redis.MultiCall) {
+    mcRep := client.MultiCall(func(mc *redis.MultiCall) {
         mc.Set("k1", "v1")
         mc.Get("k1")
     })
-    if mcallRep.Err != nil {
-        panic(mcallRep.Err)
+    if mcrep.Err != nil {
+        panic(mcRep.Err)
     }
-    mcallVal, _ := mcallRep.Elems[1].Str()
-    fmt.Println(mcallVal)
+    mcVal, _ := mcRep.Elems[1].Str()
+    fmt.Println(mcVal)
 
     // transactional calls
-    tranRep := client.Transaction(func(mc *redis.MultiCall) {
+    tRep := client.Transaction(func(mc *redis.MultiCall) {
         mc.Set("k2", "v2")
         mc.Get("k2")
     })
-    if tranRep.Err != nil {
-        panic(tranRep.Err)
+    if tRep.Err != nil {
+        panic(tRep.Err)
     }
-    tranStr, _ := tranRep.Elems[1].Str()
-    fmt.Println(tranStr)
+    tStr, _ := tRep.Elems[1].Str()
+    fmt.Println(tStr)
 
     // pubsub
     msgHdlr := func(msg *redis.Message) {
diff --git a/src/074-postgres/postgres.go b/src/074-postgres/postgres.go
index 54a09f3..c69128c 100644
--- a/src/074-postgres/postgres.go
+++ b/src/074-postgres/postgres.go
@@ -8,28 +8,39 @@ import "time"
 import "fmt"
 
 func main() {
-    db, openErr := sql.Open("postgres", "dbname=gobyexample sslmode=disable")
+    conf := "dbname=gobyexample sslmode=disable"
+    db, openErr := sql.Open("postgres", conf)
     if openErr != nil {
         panic(openErr)
     }
     defer db.Close()
     fmt.Println(db)
 
-    createRep, createErr := db.Exec("CREATE TABLE items (a int, b float, c boolean, d text, e timestamp with time zone)")
+    createRep, createErr := db.Exec(
+        `CREATE TABLE items
+         (a int, b float, c boolean,
+          d text, e timestamp with time zone)`)
     if createErr != nil {
         panic(createErr)
     }
     fmt.Println(createRep)
 
-    insertRep, insertErr := db.Exec("INSERT INTO items VALUES (1, 2.0, false, 'string', '2000-01-01T01:02:03Z')")
+    insertRep, insertErr := db.Exec(
+        `INSERT INTO items VALUES
+         (1, 2.0, false,
+          'string', '2000-01-01T01:02:03Z')`)
     if insertErr != nil {
         panic(insertErr)
     }
     fmt.Println(insertRep)
 
-    t1, _ := time.Parse(time.RFC3339, "2000-04-08T03:02:01Z")
-    t2, _ := time.Parse(time.RFC3339, "2007-03-02T10:15:45Z")
-    minsertRep, minsertErr := db.Exec("Insert INTO items VALUES ($1, $2, $3, $4, $5), ($6, $7, $8, $9, $10)",
+    timeFmt := time.RFC3339
+    t1, _ := time.Parse(timeFmt, "2000-04-08T03:02:01Z")
+    t2, _ := time.Parse(timeFmt, "2007-03-02T10:15:45Z")
+    minsertRep, minsertErr := db.Exec(
+        `Insert INTO items VALUES
+         ($1, $2, $3, $4, $5),
+         ($6, $7, $8, $9, $10)`,
         3, 7.0, true, "more", t1,
         5, 1.0, false, "less", t2)
     if minsertErr != nil {
diff --git a/src/079-request-logging/request-logging.go b/src/079-request-logging/request-logging.go
index eacb10e..812db1e 100644
--- a/src/079-request-logging/request-logging.go
+++ b/src/079-request-logging/request-logging.go
@@ -15,20 +15,21 @@ func runLogging(logs chan string) {
 func wrapLogging(f http.HandlerFunc) http.HandlerFunc {
     logs := make(chan string, 10000)
     go runLogging(logs)
-    return func(res http.ResponseWriter, req *http.Request) {
+    return func(rs http.ResponseWriter, rq *http.Request) {
         start := time.Now()
-        f(res, req)
+        f(rs, rq)
         method := req.Method
         path := req.URL.Path
         elapsed := float64(time.Since(start)) / 1000000.0
-        logs <- fmt.Sprintf("method=%s path=%s elapsed=%f", method, path, elapsed)
+        logs <- fmt.Sprintf("method=%s path=%s elapsed=%f",
+                            method, path, elapsed)
     }
 }
 
-func hello(res http.ResponseWriter, req *http.Request) {
-    res.Header().Set("Content-Type", "text/plain")
+func hello(rs http.ResponseWriter, rq *http.Request) {
+    rs.Header().Set("Content-Type", "text/plain")
     time.Sleep(time.Millisecond * 50)
-    fmt.Fprintln(res, "Hello logged world")
+    fmt.Fprintln(rs, "Hello logged world")
 }
 
 func main() {
diff --git a/src/081-basic-authentication/basic-authentication.go b/src/081-basic-authentication/basic-authentication.go
index fb31752..5a5dde9 100644
--- a/src/081-basic-authentication/basic-authentication.go
+++ b/src/081-basic-authentication/basic-authentication.go
@@ -9,10 +9,11 @@ import (
     "strings"
 )
 
-type Authenticator func(string, string) bool
+type Auth func(string, string) bool
 
-func testAuth(r *http.Request, auth Authenticator) bool {
-    s := strings.SplitN(r.Header.Get("Authorization"), " ", 2)
+func testAuth(r *http.Request, auth Auth) bool {
+    header := r.Header.Get("Authorization")
+    s := strings.SplitN(header, " ", 2)
     if len(s) != 2 || s[0] != "Basic" {
         return false
     }
@@ -28,12 +29,13 @@ func testAuth(r *http.Request, auth Authenticator) bool {
 }
 
 func requireAuth(w http.ResponseWriter, r *http.Request) {
-    w.Header().Set("WWW-Authenticate", `Basic realm="private"`)
+    w.Header().Set("WWW-Authenticate",
+                   "Basic realm=\"private\"")
     w.WriteHeader(401)
     w.Write([]byte("401 Unauthorized\n"))
 }
 
-func wrapAuth(h http.HandlerFunc, a Authenticator) http.HandlerFunc {
+func wrapAuth(h http.HandlerFunc, a Auth) http.HandlerFunc {
     return func(w http.ResponseWriter, r *http.Request) {
         if testAuth(r, a) {
             h(w, r)
diff --git a/src/082-canonical-hosts/canonical-hosts.go b/src/082-canonical-hosts/canonical-hosts.go
index 56e7897..bd9c5ac 100644
--- a/src/082-canonical-hosts/canonical-hosts.go
+++ b/src/082-canonical-hosts/canonical-hosts.go
@@ -11,7 +11,7 @@ func hello(res http.ResponseWriter, req *http.Request) {
     fmt.Fprintln(res, "Hello canonical world")
 }
 
-func wrapCanonicalHost(f http.HandlerFunc, canonicalHost string) http.HandlerFunc {
+func wrapCanonicalHost(f http.HandlerFunc, host string) http.HandlerFunc {
     return func(res http.ResponseWriter, req *http.Request) {
         hostPort := strings.Split(req.Host, ":")
         host := hostPort[0]
diff --git a/style/book.css b/style/book.css
index 2081256..17d75d1 100644
--- a/style/book.css
+++ b/style/book.css
@@ -21,6 +21,9 @@ p {
 h1, h2, h3, h4, h5, h6 {
   margin: 30px 0 15px 0;
 }
+h2 {
+  page-break-before: always;
+}
 hr {
     border: 0 none;
     border-top: 1px solid #e5e5ee;
diff --git a/tool/build-html b/tool/build-html
new file mode 100755
index 0000000..9748440
--- /dev/null
+++ b/tool/build-html
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+ls src/0*/*.{go,sh} | xargs tool/generate > build/go-by-example.html
diff --git a/tool/build-pdf b/tool/build-pdf
new file mode 100755
index 0000000..4e19766
--- /dev/null
+++ b/tool/build-pdf
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+prince build/go-by-example.html -o build/go-by-example.pdf
+