Maximal semigroups in the divisible hull of lattices in nilpotent Lie groups. do Rocio, Osvaldo Germano — 2001 Journal of Lie Theory
Semigroups in lattices of solvable Lie groups. do Rocio, Osvaldo Germano; San Martin, Luiz A.B. — 1995 Journal of Lie Theory
Free groups of semigroups in semi-simple Lie groups. do Rocio, Osvaldo Germano; Santana, Alexandre J. — 2004 Portugaliae Mathematica. Nova Série