By Booher, L.J.
By Withers, Bruce, Vipond, Stanley
By Stern, Peter
By H.T. Lovegrove
By Hunt, Roderick
By Calvin Wyatt Rose
By Agriculture, Fish.& Food, Min.of
By G. R. Dixon
By J. A. Samson
By Alec Bristow
By R.W. Widdowson (Bourne, Lincolnshire, UK)
By Nicholas Harberd
By R. L. Heathcote
By Willock, Colin
By D. L. Ebbels, John Ernest King
By Richard H. Zimmerman, Robert J. Griesbach, Freddi A. Hammerschlag, R.H. Lawson
By Elgene E. O. Box
By Great Britain: Forestry Commission
By L. R. Humphreys
By Williams, Colin Norman, Chen, W.Y., Chew, Rajaratnam, J.A.
By James L. Brewster (Horticulture Research International, Wellesbourne, UK)
By Friedheim Goeltenboth
By S. J. Kays
By N.T. Gill, K.C. Vear
By J.D. Acland
By S.C. Pearce