Freund, John E.
Prentice-Hall, 1980
Buku Teks
Freund, John E.
Prentice-Hall, 1984
Buku Teks SO
Bowley, Arthur
Macdonald and Evans, 1951
Buku Teks SO
Levin, Richard I.
Prentice-Hall, 1980
Buku Teks SO
Hoel, Paul Gerhard, 1905-
John Wiley & Sons, 1962
Buku Teks SO