erc:
who: Hill, Paul R.
what: Generalized selection charts for bombers powered by one, two, four, and six 3000-horsepower engines 1: capacity and economy
when: 19420800
where: https://digital.library.unt.edu/ark:/67531/metadc62654/
erc-support:
who: University of North Texas Libraries
what: Permanent: Stable Content:
when: 20081203
where: https://digital.library.unt.edu/ark:/67531/