Luchins, Abraham S.
Holt, Rinehart and Winston, 1965
Buku Teks
Murphey, Murray G.
Springer, 2012
eBooks
edited by Dov M. Gabbay and John Woods
Elsevier, 2004
Buku Referensi
Achmad Dardiri
Rajawali , 1986
Buku Teks
Ewing, J.H.
Student Outline Co. , 1960
Buku Teks