Bodsworth, C.
Longmans Green and Co LTD, 1963
Buku Teks
Hosford, William F.
Cambridge University Press , 2012
Buku Teks
Engel, Thomas
Pearson Prentice Hall, 2006
Buku Teks
Alberty, Robert A.
John Wiley & Sons, 1992
Buku Teks
Fried, Vojtech
McGraw-Hill, 1977
Buku Teks