On essential variables of dual operations and the consequences for operations Sebastian Kerkhoff OriginalPaper 01 June 2013 Pages: 43 - 70
Fully invariant and verbal congruence relations Clifford BergmanJoel Berman OriginalPaper 07 June 2013 Pages: 71 - 94
The order of principal congruences of a bounded lattice G. Grätzer OriginalPaper 05 June 2013 Pages: 95 - 105