Analysis of factors that cause the increasing number of ISO 14001 environmental management system non-conformances in PT Pupuk Iskandar Muda Lhokseumawe, and - , SAKTI, Rio Harjuno Aryo, Dr.Ir. Adi Djoko Guritno, M.Sie ([Yogyakarta] : Universitas Gadjah Mada, 2003)