Part 3 of Otakar Sevcik's School of Bowing Technique for Cello, Opus 2, from the Music Sales America series published by Bosworth, features numerous wrist suppleness exercises.
Sevcik's Cello School of Bowing Technique, Op. 2 Part 2, by Otakar Sevcik, is part of the Music Sales America series published by Bosworth. This excellent series covers triplets and semiquavers, developing a soft tone, sustained tones, and economizing bow length.