The sons of Leah were Reuben the firstborn of Jacob, Simeon, Levi, Judah, Issachar, and Zebulun.
Jewish Publication Society of America Version (JPS1917) - Genesis 35:23 >the sons of Leah: Reuben, Jacob's first-born, and Simeon, and Levi, and Judah, and Issachar, and Zebulun;