Generalized Casimir invariants of six dimensional solvable real Lie   algebras with five dimensional nilradical
  We finish the determination of the invariants of the coadjoint representation of six dimensional real Lie algebras, by determining a fundamental set of invariants for the 99 isomorphism classes of solvable Lie algebras with five dimensional nilradical. We also give some results on the invariants of solvable Lie algebras in arbitrary dimension whose nilradical has codimension one. 
Rutwig Campoamor-Stursberg