1. E. STARCH, M. T. H. MACKOWSKY, M. TEICHMOLLER, H. TAYLOR, D. CHANDRA and R. TEICHMOLLER (eds): 'Stach's text book of coal petrology', 3rd edn, 1981,87-88,181-187.
2. C. C. DELL: ‘Release analysis: a new tool for ore dressing research’, In Recent developments in mineral dressing, IMM, 1953, 75-84.