Blunt, Alison
Prentice-Hall, 2000
Buku Teks
Minshull, Roger
Hutchinson University Library, 1971
Buku Teks
Getis, Arthur, author
McGraw-Hill Higher Education, 2009
Buku Teks
Kendall, Henry M., author
Harcourt, Brace, 1958
Buku Teks
Getis, Arthur, author
McGraw-Hill, 2000
Buku Teks