Balasubramaniam Jayaram Michal Baczynski (U, N)-Implications and Their Characterizations. 105-110 2007 EUSFLAT Conf. (1) http://www.eusflat.org/proceedings/EUSFLAT_2007/papers/BACZYNSKI_MICHAL_(126).pdf conf/eusflat/2007-1 db/conf/eusflat/eusflat2007-1.html#JayaramB07