Bygdeman, S. et al. 1981. Serological classification of Neisseria gonorrhoeae by co-agglutination: a study of serological patterns in two geographical areas of Sweden. Acta Dermato-Venereologica. 61, 5 (Sep. 1981), 423–427. DOI:https://doi.org/10.2340/0001555561423427.