Michael S. Lewis-Beck, editor
Sage Publications, 1993
Buku Referensi
Leabo, Dick A.
Richard D. Irwin, 1968
Buku Teks SO
Lind, Douglas A.
McGraw-Hill Education, 2019
Buku Teks
Moore, David S.
W.H. Freeman, 2000
Buku Teks
Kazmier, Leonard J.
McGraw-Hill, 1984
Buku Teks