2001, William Alan Blair, William Pencak, Making and Remaking Pennsylvania's Civil War, page 107:
He made his fortune during the presteel era of Pittsburgh's development — the period before Andrew Carnegie and Henry Clay Frick — beginning in the 1820s and 1830s with a start in pharmaceuticals and white lead.
2003, William J. Mills, Exploring Polar Frontiers: A Historical Encyclopedia:
Other winterings followed in 1795 and on four occasions in the 1820s, but one in 1834–1835 ended with the death of all members of a seven-man party.