J. P. H. Kaasschieter, and T. J. A. Reijers. “Petroleum Geology of the Southeastern North Sea and the Adjacent Onshore Areas (the Hague, 1982) - Preface”. Netherlands Journal of Geosciences, Jan. 1983, p. 1, https://njgjournal.nl/index.php/njg/article/view/13341.