[Lucas G., Synge H., The IUCN Plant Red Data Book: Comprising Red Data Sheets on 250 Selected Plants Threatened on a World Scale, IUCN, Morges, 1978, s. 107–108, ISBN 2-88032-202-2]
The collection of descriptions of 250 plants contains a separate profile of Obregonia denegrii, with tubercle, areole and flower structure, limestone habitat characteristics and a historical description of collecting pressure. The chapter was prepared in collaboration with D. R. Hunt. The reading covers pages 107–108. Threat assessments and regulations in the book represent the situation in 1978.