http://repository.uhamka.ac.id/4499/
Retno Mardhiati A, RMI
http://repository.uhamka.ac.id/4499/1/Belajar%20Mandiri%201.pdf
Retno Mardhiati A, RMI Belajar Mandiri Sesi 1 MK Biostatistik Inferensial. Universitas Muhammadiyah Prof. Dr. HAMKA”. (Unpublished)