found: Sroka, Stanisław. Jadwiga Zapolya, 2005:p. 7 (Stefana Zapolyi; d. 1499) p. 129 (Stephen Zapolya, Hungarian magnate)
found: Britannica online, Dec. 11, 2006(under Sigismund I: Prince Stephen Zápolya of Hungary)
found: Columbia Encycl., 6th ed. on WWW, Dec. 11, 2006(Zápolya, Stephen; d. 1499; palatine of Hungary, 1492-99)
found: Encyclopedia of world history, 2001 on WWW, Dec. 11, 2006:(under Ladislas II: Stephen Zápolya (Szapolyai), Prince of Transylvania)
found: Slovakia and the Slovaks, 1994(under Zápol̕ský: Štefan; d. 1499)