1. Cluster models for earthquakes: Regional comparisons
2. Agterberg F. P.(1974).Geomathematics. Elsevier Amsterdam. (A course on calculus matrix algebra and probability statistics—sound but classical—followed by two chapters on spatial statistics time series Markov chains stochastic petrology directional data and multivariate analysis of spatial data.)
3. Cyclic characteristics of coal-bearing sediments in the Bochumer Formation (Westphal A 2) Ruhrgebiet, Germany