"Hills Like White Elephants" is a very short story. In the Finca Vigia Edition of The Complete Short Stories of Ernest Hemingway (Charles Scribner's Sons, 1987), that story only takes up four pages, from 211 to 214. I don't see why you should have to cite a page in such a short story. It should be sufficient to quote enough of the text so that it would be easy for anyone to find. Don't you have a printed copy of the story?