Gwersi Medr yng Nghymraeg. Ability exercises in Welsh. Llyfr parotoawl 1.
Williams, Robert T.,Joint-Author of "Ability Exercises in English".
Ashmore, A. C. Stevenson.
London, 
1933.
Joint authors: Robert T. Williams, Joint-Author of "Ability Exercises in English", and A.C. Stevenson Ashmore.