1. ARCHER = A Representative Corpus of Historical English Registers version X . 1990-1993/2002/2007/2010/2013/2016 . http://www.manchester.ac.uk/archer
2. Supplementary
online material to Baker, Peter.
2012;Glossary, Old English
Aerobics,2003–2012
3. OED = Oxford English Dictionary . 2018 . Oxford : Oxford University Press . http://www.oed.com/