Pumpelly, R., & Willis, B. (1886). Report on the mining industries of the United States (exclusive of the precious metals): With special investigation into the iron resources of the republic and into the Cretaceous coals of the Northwest. Govt.Print. Off..
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPumpelly, Raphael, और Bailey Willis. Report on the Mining Industries of the United States (exclusive of the Precious Metals): With Special Investigation into the Iron Resources of the Republic and into the Cretaceous Coals of the Northwest. Washington: Govt.Print. Off., 1886.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPumpelly, Raphael, और Bailey Willis. Report on the Mining Industries of the United States (exclusive of the Precious Metals): With Special Investigation into the Iron Resources of the Republic and into the Cretaceous Coals of the Northwest. Govt.Print. Off., 1886.