author specialist ???

There are plenty of chess authors out there and I was curious as to types of authors who specialize in a type of study for example I honestly believe Fred Reinfeld books are useful for anyone below 2000 and John Watson produces some excellent opening books. What are some authors that specialisze in a type of study/subject and what is it ?

Dvoretsky - endgames. Emms - openings. Nunn - endgame puzzles (recently). Kasparov - chess history 1980-2005. Winter - research. Wall - trivia.

who is W!all i very much like trivia

Bill Wall:

http://www.chess.com/members/view/billwall

I wrote 33 chess books, specializing in chess miniatures, irregular openings, and chess trivia.  The majority of my chess articles (over 900) are on chess trivia,chess history and chess humor.  I've probably written over 200 articles here at chess.com.