11.   He was gathering data for a book about world metro systems, a task on which he had been engaged for years.

12.   He wrote a best-selling book about the first ascent of Everest.

13.   He wrote a book about the origins of the universe.

14.   I have long been a avid reader of books about islands.

15.   I read a lot of books about astronomy.

16.   I set out to write a totally non-controversial book about a non-controversial figure.

17.   I went and got a library book about it.

18.   If so, narrow your search to books about it.

19.   In an absorbing book about how she learned to fly, Diane Ackerman tells why she chooses to risk her life.

20.   In this election year, books about politics are as plentiful as presidential primaries.