Galilei, Galileo (October 9, 2003). "The Starry Messenger"(PDF). Hudson, New York. Archived from the original(PDF) on July 6, 2004. Retrieved January 12, 2023.
Laques, P.; Vidal, J. L. (March 1979). "Detection of a new kind of condensations in the center of the Orion Nebula, by means of S 20 photocathodes associated with a Lallemand electronic camera". Astronomy & Astrophysics. 73: 97–106. Bibcode:1979A&A....73...97L. ISSN0004-6361.
Galilei, Galileo (October 9, 2003). "The Starry Messenger"(PDF). Hudson, New York. Archived from the original(PDF) on July 6, 2004. Retrieved January 12, 2023.
Laques, P.; Vidal, J. L. (March 1979). "Detection of a new kind of condensations in the center of the Orion Nebula, by means of S 20 photocathodes associated with a Lallemand electronic camera". Astronomy & Astrophysics. 73: 97–106. Bibcode:1979A&A....73...97L. ISSN0004-6361.