@article{article88081690,
title   = {On a conjectured noncommutative Beals-Cordes-type characterization},
author = {Melo, Severino Toscano do Rego and Merklen Olivera, Marcela Irene},
year = {2002},
doi = {10.1090/S0002-9939-01-06270-0},
journal   = {Proceedings of the American Mathematical Society}
}