Gaya APA

Schumann, , E, H, R. (1985). Surface Subsidence Due to the Extraction of Moderately Thick Coal Seams at Shallow Depth . : Pentech Press.

Gaya MLA

Schumann, , E., H., R.. "Surface Subsidence Due to the Extraction of Moderately Thick Coal Seams at Shallow Depth". : Pentech Press, 1985. Computer Software.