Wallace Blue was a pseudonym used by Margaret P Kraenzel. I have not yet been able to find out any biographical information under either name. If anyone knows any, please let me know.
Finding the books: reasonably easy to find in America. None were published in the UK.
Links and sources
Terri A Wear: Horse Stories, an Annotated Bibliography, Scarecrow Press, 1987
National Library of Congress
Many thanks to Lisa Catz for the photographs.
Bibliography - horse books only
The Mouse-Gray Stallion
Bobbs-Merrill Co, Indianapolis, 1957, 142 pp, illus William Moyers
Pete wants to prove to his father that he is a good judge of horses, so goes on a hunt for wild horses. However, the mouse-gray stallion proves to him that looks aren’t everything. Set in Montana.
Rain Cloud, the Wild Mustang
Lothrop, Lee & Shephard, New York, 144 pp, illus Pers Crowell
Young Readers’ Press, New York, 1967
Dave has a new neighbour, who is tricked into stealing ranch horses along with the wild ones he is running. Dave’s father however suspects Rain Cloud, Dave’s favourite wild stallion, of being the one doing the stealing.
The Persian Donkey Bead
Barnes, New York, 1960, 107 pp, illus Peter Fellin