Purnomolastu, Norbertus and Widyanti, Ratna (2018) Manajemen Perkreditan bagi Bank Perkreditan Rakyat. Brilian Internasional, Sidoarjo. ISBN 978-602-60413-8-8
Purnomolastu, Norbertus and Murhadi, Werner Ria and Widyanti, Ratna (2018) AN ANALYSIS ON THE FACTORS AFFECTING CREDIT SELECTION IN BPR TO INCRESE COMPETITIVENESS (BPR CASE STUDY IN SURABAYA). In: Abstract Book 5th International Conference on Business and Banking (ICBB V). STIE Perbanas Press, Surabaya, p. 24. ISBN 978-602-96319-9-9