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