Frediswid Sturges wrote just one book: or if that is a pseudonym, just one book under that name. Her Dowsha, the Story of a Donkey, was illustrated by K F Barker.
Finding the book
Dowsha is not difficult to find, and is usually reasonably priced when it does turn up. Very good copies in very good dustjackets are harder to source, and may be expensive.
Bibliography: pony books only
Dowsha, the Story of a Donkey, A & C Black, London, 1935, illus K F Barker. 197 pp.