diff --git a/free-programming-books-tr.md b/free-programming-books-tr.md
index 10a83b8ad..29c9c97dd 100644
--- a/free-programming-books-tr.md
+++ b/free-programming-books-tr.md
@@ -139,7 +139,7 @@
 
 * [AB2014 Ruby Programlama Dili](https://github.com/leylaKapi/AB2014-Ruby-Programlama-Dili/blob/master/Ruby_AB2014.md)
 * [Ruby](https://www.ruby-lang.org/tr/)
-* [Ruby 101](https://vigo.gitbooks.io/ruby-101/content/)
+* [Ruby 101](https://www.gitbook.com/book/vigo/ruby-101/details)
 * [Ruby Kullanıcı Kılavuzu](http://www.belgeler.org/uygulamalar/ruby/ruby-ug.html)
 * [Yirmi Dakikada Ruby](https://www.ruby-lang.org/tr/documentation/quickstart/)
 
diff --git a/free-programming-books-zh.md b/free-programming-books-zh.md
index f320d2b5b..0c2d87aaa 100644
--- a/free-programming-books-zh.md
+++ b/free-programming-books-zh.md
@@ -629,7 +629,7 @@
 
 ### Swift
 
-* [《The Swift Programming Language》中文版](https://numbbbbb.gitbooks.io/-the-swift-programming-language-/content/)
+* [《The Swift Programming Language》中文版](https://www.gitbook.com/book/numbbbbb/-the-swift-programming-language-/details)
 
 
 ### Vim
diff --git a/free-programming-books.md b/free-programming-books.md
index 27e4e8dd1..1486cab54 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -1028,7 +1028,7 @@ Original Source: [List of freely available programming books](http://web.archive
 * [Developer Workbooks](http://developer.force.com/workbook)
 * [Force.com Fundamentals](https://developer.salesforce.com/page/Force_Platform_Fundamentals)
 * [Force.com Platform Fundamentals: An Introduction to Custom Application Development in the Cloud](http://www.lulu.com/shop/salesforcecom/forcecom-platform-fundamentals/ebook/product-17381451.html)
-* [Heroku Postgres](http://www.scribd.com/doc/256342154/herokupostgres-workbooks-web-final-13-pdf) (PDF)
+* [Heroku Postgres](https://web.archive.org/web/20131209081736/http://media.developerforce.com/workbooks/HerokuPostgres_Workbooks_Web_Final.pdf) (PDF)
 
 
 ### Forth
@@ -1526,7 +1526,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Google's Objective-C Style Guide](http://google-styleguide.googlecode.com/svn/trunk/objcguide.xml)
 * [Object-Oriented Programming with Objective-C](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/OOP_ObjC/OOP_ObjC.pdf) (PDF)
 * [Objective-C Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/objective-c) (PDF, Kindle) *(Just fill the fields with any values)*
-* [Programming With Objective-C](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/Introduction/Introduction.html) (PDF)
+* [Programming With Objective-C](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/Introduction/Introduction.html)
 * [Try Objective-C Book](http://tryobjectivec.codeschool.com)
 
 
@@ -1815,7 +1815,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Advanced R Programming](http://adv-r.had.co.nz) - Hadley Wickham
 * [Introduction to Probability and Statistics Using R](http://cran.r-project.org/web/packages/IPSUR/vignettes/IPSUR.pdf) - G. Jay Kerns (PDF)
 * [Learning Statistics with R](http://health.adelaide.edu.au/psychology/ccs/teaching/lsr/) - Daniel Navarro
-* [learnR](https://github.com/wh1100717/learnR) - (Work in Progress) - Kun Ren
+* [learnR](https://github.com/yuanlisky/learnR) - (Work in Progress) - Kun Ren
 * [Practical Regression and Anova using R](http://cran.r-project.org/doc/contrib/Faraway-PRA.pdf) - Julian J. Faraway (PDF)
 * [R by example](http://www.mayin.org/ajayshah/KB/R/index.html)
 * [R for spatial analysis](http://www.columbia.edu/~cjd11/charles_dimaggio/DIRE/resources/spatialEpiBook.pdf) (PDF)