Harary, Frank; Kabell, Jerald A.; McMorris, F. R. Interval acyclic digraphs. (English) Zbl 0711.05024 Ars Comb. 29A, 59-64 (1990). MSC: 05C20 06A07 PDFBibTeX XMLCite \textit{F. Harary} et al., Ars Comb. 29A, 59--64 (1990; Zbl 0711.05024)
Blass, Andreas; Harary, Frank Deletion versus alteration in finite structures. (English) Zbl 0506.05038 J. Comb. Inf. Syst. Sci. 7, 139-142 (1982). MSC: 05C35 05C20 05C99 PDFBibTeX XMLCite \textit{A. Blass} and \textit{F. Harary}, J. Comb. Inf. Syst. Sci. 7, 139--142 (1982; Zbl 0506.05038)