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1955. The excised embryo method for testing germination quality of dormant seed. 



N.Y. State Agr. Exp. Sta. J. Pap. 1013, 9 pp. 



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1940. Coniferous tree seed testing and factors affecting germination and seed quality. 

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1912. Pinus ponderosa and Pinus jeffreyi. Muhlenbergia 8: 73-79. 



(772) Heller, R. C, J. L. Bean, and F. B. Knight. 



1959. Aerial surveys of Black Hills beetle infestations. U.S. Forest Serv. Rocky 

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(773) Hellmers, Henry. 



1962. Physiological changes in stored pine seedlings. U.S. Forest Serv. Tree Plant- 

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1956. Exogenous substrate utilization and fermentation by the pollen of Pinus ponder- 



osa. Plant Physiol. 31: 284-289. 



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1943. Ecological anatomy of ponderosa pine needles. Amer. Midland Natur. 29: 55-71. 



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1946. Pruning wound healing on western white and ponderosa pines. U.S. Forest 



Serv. Northern Rocky Mountain Forest and Range Exp. Sta. Res. Note 45, 

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1946. Results of direct seeding ponderosa pine. U.S. Forest Serv. Northern Rocky 

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1948. Early results from thinning seed spots. U.S. Forest Serv. Northern Rocky 



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1944. Effects of fire on steep mountain slopes in central Arizona. J. Forest. 42: 



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1959. Grading southwestern ponderosa pine logs. Colo. State Univ. Coll. Forest 

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1964. Damage to forests from air pollution. J. Forest. 62: 630-634. 



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1949. Use of "Ammate" for poisoning ponderosa pine in stand improvement. U.S. 



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1950. Survival of fire-damaged ponderosa pine. A progress report. U.S. Forest 



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1954. A guide for marking fire-damaged ponderosa pine in the Southwest. U.S. For- 

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49 



