[1] R. Biswas, Vague groups, Internat. J. Comput. Cognition, 4(2) (2006), 20-23.
[2] H. Bustince and P. Burillo, Vague sets are intuitionistic fuzzy sets, Fuzzy Sets and Systems,
79 (1996), 403-405.
[3] W. L. Gau and D. J. Buehrer, Vague sets, IEEE Transactions on Systems, Man and Cybernetics,
23 (1993), 610-614.
[4] G. Georgescu and A. Iorgulescu, Pseudo MV-algebras, Multi. Val. Logic, 6 (2001), 95-135.
[5] A. Lu and W. Ng, Vague sets or intuitionistic fuzzy set for handling vague data: which one
is better?, Lecture Notes in Computer Science, 3716 (2005), 401-466.
[6] A. Walendziak, On implicative ideals of pseudo MV-algebras, Sci. Math. Jpn. Online, e-2005
(2005), 363-369.
[7] L. A. Zadeh, Fuzzy sets, Inform. Control, 8 (1965), 338-353.