Casimir already had two sons : Ziemomysł of Kuyavia and Leszek II the Black from his first marriage to Constance of Silesia .
Head entity: ziemomysł of kuyavia Q2033309 6 7 8
Tail entity: constance of silesia Q5163600 19 20 21
Relation (head \u2192 tail): P25
Inverse relation (tail \u2192 head): P40