*[Object-Oriented Programming with Objective-C](https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/OOP_ObjC/Introduction/Introduction.html#//apple_ref/doc/uid/TP40005149)
*[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)