Coba jelasin Lihat pula dari Henryk Brodaty dong

Cawley, Charles; Foundation for Medieval Genealogy, Medieval Lands Project; Silesia v3.0; Dukes of Breslau (Wrocław) and Lower Silesia 1163-1278 (Piast) (Chap 4); Heinrich I Duke of Lower Silesia; retrieved May 2015.