Source: “Despot Đurađ Branković: gospodar srbima, podunavlju i zetskom primorju” By Čedomilj Mijatović, 1880, page 128.
Brief translation into English:
there are large numbers of Christians, Greeks, Bulgarians, Macedonians, Albanians, Slovenes, Vlachs, Serbs and others
This book describes the period 1427-1444 in Serbian historiography, written in 1880.