Bantam Bokkc, 1954
Koleksi Publik
Sartain, Libby, author
Amacom , 2003
Buku Teks
Sartain, Libby, author
[American Management Association, ], 2003
eBooks
Seymour, Rogers James
Prentice-Hall, 1981
Buku Teks
Watchtower Bible and Tract Society, 2003
Buku Teks