BI Vul

References

1. Bradstreet1985
   Bradstreet, D.H. “K-type Overcontact Binaries”: Astrophysical Journal Supplement Series, Volume 58, pp. 413-437
   http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?bibcode=1985ApJS...58..413B&db_key=AST&high=3f4e41847224079