17 1 10 Boyce,J.S Additional Author Haresign, W. Additional Author mixed material New York McGraw- Hill Book Company, Inc. 1961 Baranyay,J.A, Bourohier,R.J and Thomas,G.P Additional Author mixed material Canada Department of Forestry of Canada 1962 Zabel,R.A Additional Author mixed material New York Department of Forest Botany and Pathology State University Of New York 1955 Zabel,R.A Additional Author mixed material New York Department of Forest Botany and Pathology State University Of New York 1955 Crutachfield, Stephen R. Additional Author Hirt,R.R. Additional Author mixed material New York Department of Botany and Pathology 1936 Boyce,J.S Additional Author Andrewartha, H.G. Additional Author mixed material New York McGraw- Hill Book Company 1961 Hirt,R.R. Additional Author Shahida Baqar Additional Author mixed material USA Department of Forest Botany and Pathology State University Of New York 1955 Boyce,J.S Additional Author Mulder, D. Additional Author mixed material New York McGraw- Hill Book Company 1961 Boyce,J.S Additional Author mixed material New York McGraw- Hill Book Company 1961 Erskine, W. Additional Author Boyce,J.S Additional Author mixed material New York McGraw- Hill Book Company 1948