Paolo Boldi Violetta Lonati Roberto Radicioni Massimo Santini The number of convex permutominoes. 1074-1083 2008 206 Inf. Comput. 9-10 http://dx.doi.org/10.1016/j.ic.2008.03.009 db/journals/iandc/iandc206.html#BoldiLRS08