H.W.Fowler and F.G.Fowler, The Concise Oxford Dictionary of Current English ,5th
ed.(Oxford,1964),39.
2
B. Kirkpatrick , Cassell Giant Paperback Dictionary(London,1993),39.
3
M.A. El-Banhawy and Others, Text Book of Zoology, 6th ed. (Cairo, 1984),446; C.Eason
,Fabulous Creatures ,Mythical Monsters ,and Animal Power Symbols( New York, 2007),131.
4
H.R.Heusser , 'Higher Anurance ', in H.C.B. Grizimek(ed.), Grizimek's Animal Encyclopedia
,5 , Fishes , II , amphibians( New York, 1974),397
5
El-Banhawy and Others, Text Book of Zoology,6th ed.,446.