Delvaux, B., Herbillon, AJ., Dufey, J., & Vielvoye, L. (1990). Surface-properties and Clay Mineralogy of Hydrated Halloysitic Soil Clays .1. Existence of Interlayer K+ Specific Sites. Clay Minerals : journal of the European Clay Groups, 25(2), 129-139. https://doi.org/10.1180/claymin.1990.025.2.01 (Original work published 1990)