1. Bogue, S. W. & Hoffman, K. A. Rev. Geophys. 25, 910–916 (1987).
2. Hoffman, K. A. Scient. Am. 256, 76–83 (1988).
3. Laj, C., in The Encyclopedia of Solid Earth Geophysics (ed. James, D. E.) 535–547 (Van Nostrand Reinhold, New York, 1989).
4. Hoffman, K. A. in The Encyclopedia of Solid Earth Geophysics (ed. James, D.E.) 547–555 (Van Nostrand Reinhold, New York, 1989).
5. Clement, B. M. & Constable, C. G. Rev. Geophys. Suppl.: U.S. Nation Rep. to Int. Un. Geodesy Geophys. 1987–1990, 343–348 (1991).