“On the nature of the PHL objects. Identification charts of PHL objects in a field of approximately 40 square degrees centered at 0h53m and -11°.5 (1950)”., RMxAA, vol. 15, no. 1, pp. 107–116, Jan. 1987, Accessed: Dec. 11, 2025. [Online]. Available: https://astronomia.unam.mx/journals/rmxaa/article/view/1987rmxaa..15..107h