In their account http://dx.doi.org/10.1016/0022-4049(87)90048-X of Sjogren's theorem, Cliff and Hartley refer to two articles: [9] B. Hartley, A note on a lemma of Sjogren relating to. dimension subgroups, Research Report 229, Department of Mathematics, National University of Singapore, 1985. [21] G.E. Wall, to appear. (!) I am especially interested in the second reference, but no article by G.E. Wall from that period seems to match the (somewhat terse) citation. Does someone have a scanned copy of these prepublications? Many thanks in advance