Relation of rooting response to age of tissue at the base of greenwood cuttings
by: A.E. Hitchcock en P.W. Zimmerman
Changes in leaves during the night
by: F.E. Denny
The origin of adventitious roots in cuttings of Portulaca Oleracea L.
by: Mary H. Connard and P.W. Zimmerman
The Nursery Book (plubished in 1896)
A complete guide to the multiplication of plants
by: L.H. Bailey
by: P.W. Zimmerman
The sesponse of roots to "Rootforming" substances
by: P.W. Zimmerman and A.E. Hitchcock
Microchemical studies of rooting and non-rooting rose cuttings
by: Margery C. Carlson
Several chemical growth substances which cause initiation of roots and other responses in plants
by: P.W. Zimmerman and Frank Wilcoxon
Tobacco as a test plant for comparing the effectiveness of preparations containing growth substances
by: A.E. Hitchcock
by: Kenneth V. Thimann and F.W. Went