Aside from the great mass of sworn testimony accessible to the student, there was a large pamphlet literature dealing with different phases of the subject, as well as files of the numerous daily newspapers and monthly reviews, supported by the Oil Region, in the columns of which were to be found, not only statistics, but full reports of all controversies between oil men. But the documentary sources were by no means all in print. The Standard Oil Trust and its constituent companies had figured in many civil suits, the testimony of which was in manuscript in the files of the courts where the suits were tried. I had supposed it would be easy to locate the records of the important investigations and cases, but I soon found I had been too trustful. For instance, there was a Federal investigation of the South Improvement Company, the first attempt to make a hard and fast alliance between oil-bearing railroads and oil refiners, an alliance which inevitably would kill everybody not admitted, since by the contract the railroads not only allowed the privileged refiners a rebate on all their shipments, but paid them a drawback on those of independents. The railroads also agreed to give them full information about the quantity and the destination of their rivals’ shipments. The Standard Oil Company as a monopoly had grown out of this pretty scheme. Where could I get a copy of that investigation? More than one cynic said, “You’ll never find one—they have all been destroyed.” When I had located copies in each of two private collections I was refused permission to put my hands on them. To be sure, I did by persistent searching find that so-guarded investigation in a pamphlet which is one of the three which are all I know to be in existence. I am not supposing that there are not others, for I quickly learned, when I was told that the entire edition of a printed document had been destroyed, to go on looking. Once a document is in print, somewhere, some time, a copy turns up, however small the edition. For instance, there was the important Hepburn investigation of the relations of railroads and private industries made by the State of New York in 1879. I could not find a copy in the Oil Region where I was working. The Standard had destroyed them all, I was told. At that time there was in the Public Library of New York City one of the ablest of American bibliographers—Adelaide Hasse. She had helped me more than once to find a scarce document. “How about this Hepburn investigation?” I wrote Miss Hasse. “Here in the Library for your use whenever you will come around.” But she added: “Only one hundred copies were ever published. It is a scarce piece. I have known of a complete set selling for $100.00. It was understood at the time,” she explained, “that one or two important railroad presidents whose testimony was given before the committee bought up and destroyed as many sets as they could obtain.”