Cross reference
Genesis 38:4
4 and she conceiveth again, and beareth a son, and calleth his name Onan;
Genesis 46:12
12 And sons of Judah: Er, and Onan, and Shelah, and Pharez, and Zarah, (and Er and Onan die in the land of Canaan.) And sons of Pharez are Hezron and Hamul.
Numbers 26:19
19 Sons of Judah `are' Er and Onan; and Er dieth -- Onan also -- in the land of Canaan.