Dobson, James
Love must be tough / James Dobson
Kingsway Pubb., 1987
 Buku Teks
Research topics
Jakarta : FK-UI, 2005,
 Majalah, Jurnal, Buletin
Batten, J.D.
Tough-minded management / J. D. Batten
D.B. Taraporevala Sons & Co., 1963
 Buku Teks
Denny J.A.
Various topics in comparative politics
Jayabaya University Press , 1999
 Buku Teks SO
Research topics in functional programming
edited by David A. Turner
Addison-Wesley, 1990
 Buku Teks