Tombaugh, C. W. (October 1937). "The Great Perseus-Andeomeda Stratum of Extra-Galactic Nebulae and Certain Clusters of Nebulae Therein as Observed at the Lowell Observatory". Publications of the Astronomical Society of the Pacific. 49: 259. Bibcode:1937PASP...49..259T. doi:10.1086/124840. ISSN0004-6280.
Bernheimer, W. E. (July 1932). "A Metagalactic Cloud between Perseus and Pegasus". Nature. 130 (3273): 132. doi:10.1038/130132a0. ISSN0028-0836.
Tombaugh, C. W. (October 1937). "The Great Perseus-Andeomeda Stratum of Extra-Galactic Nebulae and Certain Clusters of Nebulae Therein as Observed at the Lowell Observatory". Publications of the Astronomical Society of the Pacific. 49: 259. Bibcode:1937PASP...49..259T. doi:10.1086/124840. ISSN0004-6280.
Tombaugh, C. W. (October 1937). "The Great Perseus-Andeomeda Stratum of Extra-Galactic Nebulae and Certain Clusters of Nebulae Therein as Observed at the Lowell Observatory". Publications of the Astronomical Society of the Pacific. 49: 259. Bibcode:1937PASP...49..259T. doi:10.1086/124840. ISSN0004-6280.
Bernheimer, W. E. (July 1932). "A Metagalactic Cloud between Perseus and Pegasus". Nature. 130 (3273): 132. doi:10.1038/130132a0. ISSN0028-0836.