Internet : https://archon.library.illinois.edu/?p=collections/controlcard&id=3150
(2020-05-06)
LCNA (CD OCLC), 1993-12 : Day, Mahlon Marsh. Encyclopedic dictionary of mathematics,
1987 : Day, Mahlon Marsh, 1913-
Normed linear spaces / Mahlon M. Day, 1973