"Ultramar" . . . . . . . . . . . . "Diamond Shamrock" . . . . . . . . . . . . . . . . . . . . . . . . . . . . "Ultramar" . . . . "Ultramar Corporation" . . "overseas possession" . "Ultramar Diamond Shamrock Corporation" . . . . . . . "1961" . "Ultramar Limited" . . . .