Oxford junior encyclopaedia 
Salt, Laura Enid.
Boumphrey, Geoffrey,1894-
Sinclair, Robert.
Petter, Helen Mary.
Voysey, Annesley.
Moult, Edward W.
West, A. J. H.
London Oxford University Press,
1974
In 13 vols
Second ed. originally published: 1964
Children's encyclopedias and dictionaries.