Jianming Zhan Wieslaw A. Dudek Young Bae Jun Interval valued (in, in v, q)-fuzzy filters of pseudo BL-algebras. 13-21 2009 13 Soft Comput. 1 http://dx.doi.org/10.1007/s00500-008-0288-x db/journals/soco/soco13.html#ZhanDJ09