Ritonga, Abdul Rahman text Jakarta Lembaga Penerbit Fakultas Ekonomi Universitas Indonesia 1997 ind xi, 214 hlm.: ilus.; 21 cm. Abdul Rahman Ritonga Bibliografi: hlm. 212-214 Alam Semesta 523.12 979-8140-77-X STPDPAL 190705 20110419144805.0 SULTE-04110000000291 Converted from MARCXML to MODS version 3.5 using MARC21slim2MODS3-5.xsl (Revision 1.106 2014/12/19)