1. Der Kern, eine charakteristische Untergruppe, Compositio Math. 1 (1934), 254–283.
2. The decomposition of enumerable, primary, abelian groups into direct summands, Quart. J. Math. Oxford 6 (1935), 217–221.
3. The decomposition of abelian groups into direct summands, Quart. J. Math. Oxford 6 (1935), 222–232.
4. Types of elements and characteristic subgroups of abelian groups, Proc. London Math. Soc. 39 (1935), 481–514.
5. The subgroup of the elements of finite order of an abelian group, Ann. Math. 37 (1936), 766–781.