21.   His books are enormously easy to read, yet he is a serious artist.

22.   He could never have foreseen that one day his books would sell in millions.

23.   His books are notoriously impenetrable.

24.   His books are noted for their wry humor.

25.   Do his books have any literary merit?

26.   His books are popular among members of the younger generation.

27.   His books are in high demand.

28.   Demand for his books has remained low.

29.   Swainson was suggesting, even before Gould had returned to England, that he would do better to make his books more generally affordable.

30.   Although she had never read any of his books, she was well aware of the high regard he was held in in the literary world.