Journal of Combinatorial Theory, Series AVolume 19, Issue 3, November 1975, Page 367ErrataAuthor links open overlay panelShow moreShareCitehttps://doi.org/10.1016/0097-3165(75)90058-8Under an Elsevier user licenseopen archivePrevious article in issueNext article in issueRecommended articlesCited by (0)Copyright © 1975 Published by Elsevier Inc.