Ida Tarbell,
The History of the Standard Oil Company…
(1904)
“ It is sufficiently accurate for general purposes of comparison. It would be an almost impossible task to determine a "true average" from the reports of the daily sales that are now on record. Previous to 1875 the quotations are given for points along Oil Creek, and they hardly represent what the producer actually realised for oil at the wells. From 1875 onward the trading in oil was placed on a more satisfactory basis by the general adoption of pipe-line certificates, and the exchange quotations show very closely the value of the oil at the wells. ”
