Arithmetic of the module of roots of the isogeny of a formal group in the case of small ramification

In this paper, for a one-dimensional formal group over the ring of integers of a local field in the case of small ramification we study the arithmetic of the module of roots of the isogeny, as well as the arithmetic of the formal module constructed on the maximal ideal of a local field containing all the roots of the isogeny. Bibliography: 5 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 338, 2006, pp. 125–136.