Hopkins, John C.Krause, Federico F.2007-05-022007-05-021993-06Hopkins, J. C. and Krause, F. F. (1993). "Penetrative calcretes and their stratigraphic implications: Comment and Reply". Geology, 21, No.6: 572-573.0091-7613http://hdl.handle.net/1880/44575engGeologyGeophysicsGeology-Stratigraphicjournal article10.11575/PRISM/35052