1. Karayigit, A. İ. 1989. Petrograghical properties of Zonguldak ve Amasra Coal. PhD diss., Graduate School of Natural and Applied Science, Hacettepe University.
2. Oney, O. 1993. The enrichment of Zonguldak fine coal by flotation. PhD diss., Graduate School of Natural and Applied Science, Dokuz Eylul University.
3. Influence of petrographical composition on coal flotability