1. G. Bodvarsson, Physical Characteristics of Natural Heat Resources in Iceland, U. N. Conference on New Sources of Energy, Rome, 1961.
2. G. P. L. Walker, Quart. J. Geol. Soc. Lond., 119, 29, 1963.
3. K. Saemundsson, Natturufradingurinn, 42, 8l, 1972.
4. G. P. L. Walker, Bull. Volcanologique 29, 375, 1966.
5. H. Sigurdsson, Soc. Sci. Islandica, Greinar IV, 2, 1966.