Braun, Robert D., author
McGraw-Hill, 1987
Buku Teks
by Hobart H. Willard ... [et al.]
Wadsworth, 1988
Buku Teks
Harley, John H., author
John Wiley & Sons, 1954
Buku Teks
Rakel, David
saunders, 2007
Multimedia
Willard, Hobart H. (Hobart Hurd), 1881-1974, author
D. Van Nostrand Company , 1958
Buku Teks