1. Specification for Oil-Well Drilling Fluid Materials;API (American Petroleum Institute),1988
2. Arnold, D., 1967. Sak Lu'um in Maya culture and its possible relation to Maya Blue. PhD thesis, Dept. of Anthropology, Univ. of Illinois.
3. Ethnomineralogy of Ticul Yucatan potters;Arnold;Am. Antiq.,1971
4. Attapulgite and Maya Blue: an ancient mine comes to light;Arnold;Archaeology,1975
5. Chemical analysis;Bain,1987