How did John D. Rockefeller gain control of 90 percent of the oil refining business by 1890?

He first used horizontal Integration, by buying up all the oil refining companies and putting them under the name of Standard Oil. Then he used vertical Integration by buying up all the companies that were related in the oil business. Like: Oil fields, drilling operation, shipping (railroad), refining, wholesale, and even retail gas stations. Some said he owned all the way down to the companies that made the barrels that the oil was shipped in.