Cooks i am researching

I am researching my fathers people. My father was Donnie Raymond Cook, born in Slayton, Texas.
He died in Houston, Tx.
His parents was Julius E. Cook and Gladys Crumbly, Julius was from Quitman, Texas July 17, 1909
She was born Ben Franklin, Tx 22 July 1917.

Julius father was Thomas C Cook, birth abt 1866, Texas. The 1910 census stated that his fathers birth place was Ireland and his mothers Alabama.
My brick wall is with his father Cornelius Cook and wife unknown.