The author thanks Martin Wursthorn, who pointed out that the supposedly distinct 2-groups H(m, 1) and H(m, 3), defined on page 588 of [1], are in fact isomorphic to each other. This is an error (rather than a misprint), but may be corrected by changing the presentations of H(m, q) and H˜ as follows. Replace the relation B4=1 in the presentation for H(m, q) by the relation B8=1, and replace the relation Y4=1 in the presentation for H˜ by the relation Y8=1. With these modifications, the paragraph concerning the groups H(m, q) becomes valid.