1. Tissot BP, Welte DH (1984) Petroleum formation and occurrence–a new approach to oil and gas exploration Springer. Berlin Heidelberg New York
2. Van Krevelen DW (1961 1 Coal. Elsevier
3. Thurstone LL (1947) Multiple-factor analysis. University of Chicago Press, Chicago London
4. Horst P (1964) Factor analysis of data matrices. Holt, Rinehart and Winston, New York Chicago London
5. Rummel RJ (1970) Applied factor analysis. Northwestern University Press, Evanston, IL