Gallup, George
McGraw-Hill, 1982
Buku Teks SO
Neimark, Edith D.
Harcourt Brace Javanovich, 1987
Buku Teks SO
Whitehead, Alfred North, 1861-1947
New American Library, 1933
Buku Teks
edited by Matthew Beaumont
Blackwell, 2007
Buku Teks SO
Rasmussen, Steen Eiler
Technology Press of Massachusetts Institute of Technology, 1975
Buku Teks SO