Frank, Walter Smoter (maio de 1988). "The Cause of the Johnstown Flood". Civil Engineering: 63–66. Arquivado dende o orixinal o 06 de abril de 2019. Consultado o 06 de abril de 2019.
time.com
listed at 372 billion 2014 USD by Jacob Davidson, time.com The 10 Richest People of All TimeArquivado 13 de abril de 2019 en Wayback Machine. "Rockefeller gets all the press, but Andrew Carnegie may be the richest American of all time. The Scottish immigrant sold his company, U.S. Steel, to J. P. Morgan for $480 million in 1901. That sum equates to slightly over 2.1 percent of U.S. GDP at the time, giving Carnegie an economic power equivalent to $372 billion in 2014."
web.archive.org
listed at 372 billion 2014 USD by Jacob Davidson, time.com The 10 Richest People of All TimeArquivado 13 de abril de 2019 en Wayback Machine. "Rockefeller gets all the press, but Andrew Carnegie may be the richest American of all time. The Scottish immigrant sold his company, U.S. Steel, to J. P. Morgan for $480 million in 1901. That sum equates to slightly over 2.1 percent of U.S. GDP at the time, giving Carnegie an economic power equivalent to $372 billion in 2014."
Frank, Walter Smoter (maio de 1988). "The Cause of the Johnstown Flood". Civil Engineering: 63–66. Arquivado dende o orixinal o 06 de abril de 2019. Consultado o 06 de abril de 2019.
