Gender-less book

Is there any books that use 'they', 'them' and 'theirs' instead of 'he', 'she', 'him', 'her', 'his' and 'hers'?

I wanna see what genders people happen to assign the characters.

>>1
I thought "they" was only to be used for more than one person.
Wouldn't using "him/her", while awkward, be grammatically correct?