@article{ Solr-acta16332, title = {Notes on planar semimodular lattices. IV. The size of a minimal congruence lattice representation with rectangular lattices}, series = {Acta scientiarum mathematicarum}, author = {Grätzer George A.}, year = {2010}, url = {http://acta.bibl.u-szeged.hu/16332/1/math_076_numb_001_002_003-026.pdf} }