Hardle, Wolfgang Karl
Springer, 2012
eBooks
Johnson, Richard A.
Pearson Education International, 2007
Buku Teks SO
Kachigan, Sam Kash
Radius Press, 1991
Buku Teks SO
Hardle, Wolfgang Karl
Springer , 2012
eBooks
Dunteman, George Henry
Sage Publications, 1984
Buku Teks