@techreport{R-91-23,
TITLE = {Constructive Negation by Fail Answers},
AUTHOR = {Wlodzimierz Drabent},
YEAR = {1991},
NUMBER = {R-91-23},
INSTITUTION = ida,
ADDRESS = idaaddr,
ABSTRACT = {},
IDANR = {LiTH-IDA-R-91-23},
NOTE = {Also published in the Journal Acta Informatica, 1992}