Xg. Zou et Yh. Xu, DECOMPOSITION OF COMODULES, Science in China. Series A, Mathematics, Physics, Astronomy & Technological Sciences, 37(8), 1994, pp. 946-953
It has been proved, using a special approach, that any comodules over
a field can be uniquely decomposed into the direct sum of closed indec
omposable subcomodules.