Spencer, J.E.
John Wiley & Sons, 1969
Buku Teks
Crang, Mike
Routledge, 1998
Buku Teks
Bennison, George Mills
Routledge, 2013
Buku Teks
Getis, Arthur
McGraw-Hill Higher Education, 2009
Buku Teks
Kendall, Henry M.
Harcourt, Brace & World, 1962
Buku Teks