
Comet Mrkos 1957d [JRASC 51,323 [2]].
Links:
[1] http://www.rasc.ca/category/image-galleries/national-archives/archives-1950s-jrasc-0
[2] http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1957JRASC..51..323.&db_key=AST&link_type=GIF&high=4904d723c621201