Sort:  
 last month 

What kind of reference? I wrote everything I learned in my class. I studied Chemistry for 8 long years and all my textbook is my reference.

 last month 

It would be better if you add a little note, that the references in this article come from several books that I have read, and don't forget to mention the name of the book and the author.

 last month 

Well. Added the note, will remember this for the future.