Chartrand, Gary
McGraw-Hill, 2005
Buku Teks SO
Morris, William T.
Richard D. Irwin, 1962
Buku Teks SO
Nora Hartsfield
Academic Press , 1990
Buku Teks SO
editor, Bela Bollobas
North-Holland , 1982
Buku Teks SO
Gould, Ronald
The Benjamin Cumming , 1988
Buku Teks SO