Binhadi
Institut Bankir Indonesia, 1995
Buku Teks SO
Mehmet Ezer
Bank Indonesia Institute, 2019
Artikel Jurnal
Hamberg, Daniel
Little, Brown and company , 1981
Buku Teks
Woodworth, George Walter
McGraw-Hill, 1950
Buku Teks
Rifki Ismail
John Wiley & Sons, 2013
Buku Teks SO