J. Theo Kloprogge, Ad M.J. van der Eerden, J. Ben H. Jansen, and John W. Geus. “Hydrothermal Synthesis of Na-Beidellite”. Netherlands Journal of Geosciences, Jan. 1990, pp. 351-7, https://njgjournal.nl/index.php/njg/article/view/12876.