http://vocabularios.caicyt.gov.ar/uat/ Unified Astronomy Thesaurus UAT UAT 2013-12-18 en 2013-12-18 17:18:15 Yerkes classification 2013-12-18 17:18:15 MK classification MKK classification Yerkes spectral classification http://vocabularios.caicyt.gov.ar/uat/skos/198