Since I had hard time fully understanding how to site with APA style, I will post on it. I hope it will remind me later and hopefully somebody will get something out of it.

According to MD HIRO, for the researchers on social science such as Education, APA style is the most used one.

Say MD(Last name) HIRO(First name) published the book on APA style, titled “Susume de MD on APA” in 2012 from OK University, the above mentioned phrase would be like this.
According to MD (2012), “for the researchers on social science such as Education, APA style is the most used one” (p. 515). <=period always follows parenthesis!!

OR

“For the researchers on social science such as Education, APA style is the most used one” (MD, 2012, p. 515).

When you put reference, it would be the following
Reference:
MD, HIRO. (2012). Susume de MD on APA (2nd edition): OK University

Just like that!!