Catalogue of Malay, Minangkabau, and South Sumatran manuscripts in the Netherlands; Volume 2
compiled by Teuku Iskandar
Documentatieburean Islam-Christendom , 1999
 Buku Referensi
Catalogue of Malay, Minangkabau, and South Sumatran manuscripts in the Netherlands : volume 1 / compiled by Teuku Iskandar
Leiden, Documentatieburean Islam-Christendom
 Buku Referensi
Duality of existence
 Artikel Jurnal
Rockafellar, R. Tyrrell
Conjugate duality and optimization
Society for Industrial and Applied Mathematics, 1974
 eBooks
Cornes, Richard
Duality and modern economics / Richard Cornes
Cambridge University Press , 1992
 Buku Teks