1. Abraham, H. 1960.Asphalts and allied substances: Their occurrence, modes of production, uses in the arts, and methods of testing, vol 1. Historical review and natural raw materials, 370Van Nostrand.
2. Alm, E. and Sundblad, K. 2002.Fluorite-calcite-galena-bearing fractures in the counties of Kalmar and Blekinge, Sweden, 116Swedish Nuclear Fuel and Waste Management Co. R-02-42. ISSN: 1402-3091.
3. Secular, episodic changes in stable carbon isotope composition of crude oils