Tester, Keith
Routledge, 1992
Buku Teks
Symon, Keith R.
Addison-Wesley, 1971
Buku Teks
Keith, Harold
A HarperKeypoint Book, 1957
Buku Teks
Taylor, Richard
Englewood Cliffs : A Simon & Schuster, 1992
Buku Teks
Taylor, Edmond
Houghton Miffiln, 1947
Buku Teks