Need articles that covers complete tutorials (with syntax) for LINQ or ENTITY FRAMEWORK? Like MozillaDeveloper.

No, You don't need to learn Linq before Entity framework, you need to have basic knowledge of it, and alternative is lambda expression using entity framework

For EF tutorial, Which tutorial do you need Code first or Database First approach?

Entity framework tutorial links

For basic connectivity using code first here is the article

https://qawithexperts.com/article/asp.net/code-first-migration-with-entity-framework/51

If you need connecting to database using Database first approach in EF in MVC

https://qawithexperts.com/article/asp.net/mvc-tutorial-part-2-connecting-to-database-fetchinginserting/29

Now about complete tutorial website, I find this website helpful

http://www.entityframeworktutorial.net/ which has both code first approach and database first explained.

EF complete details by microsoft https://msdn.microsoft.com/en-us/data/ee712907

PDF link : http://it-ebooks.directory/book-1430257881.html

Linq tutorial

Few website links http://www.tutorialsteacher.com/linq/linq-tutorials

http://tutlane.com/tutorial/linq

https://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b (The one which you mentioned I think)

http://it-ebooks.directory/book-1933988169.html

If you want more tutorial, there are many courses on Udemy and pluralsight, which is paid but i don't recommeed it personallly when you already have lots of website's tutorial and pdf available to download for free.

But you will learn it most when you will start coding in it.