Laravel eloquent and query builder definitive guide

http://codeplanet.io/laravel-model-relationships-pt-1/

https://scotch.io/tutorials/a-guide-to-using-eloquent-orm-in-laravel

http://www.easylaravelbook.com/blog/2015/03/05/introducing-the-one-to-one-relationship/

http://laravel-tricks.com/tricks/correctly-using-eloquent-relationships

http://christoph-rumpel.com/2014/09/conditional-queries-in-laravel-4/

http://jenssegers.com/51/laravel-collections-are-awesome

http://www.neontsunami.com/posts/dynamic-where-clauses-and-find-methods-in-eloquent-%28laravel-4%29