Here are the books in the series:
* All Creatures Great and Small (1970)
* All Things Bright and Beautiful (1974)
* All Things Wise and Wonderful (1977)
* The Lord God Made Them All (1981)
He also wrote a few other books:
* A Treasury of James Herriot (1996) - A collection of stories from the series and other writings.
* James Herriot's Yorkshire (1997) - A book about the Yorkshire Dales, where Herriott lived and worked.
It's worth noting that Frank Wilbur Herriott was the real name of James Herriot, the pen name he used for his writing.