Informazzjoni minn organizzazzjoni tal-arti (Verifikat minn Operabase)
Bulgarians From Olden Times by Karastoyanov, Tne 19 Set 2011, Minn (2011/2012), Immexxi minn Nikolay Aprilov,, Surmast Direttur Stanislav Ushev, Krasimir Kashev, Opera Theatre, Varna, Bulgaria