Rooting of Cuttings from plants sprayed with Growth Regulating Substances
door: V.T. Stoutemeyer and F.L. O'Rourke

Growth Hormones in Plants
door: Kenneth V. Thimann 

Stomatal Function
door: Eduardo Zeiger, G.D. Farquhar and I.R. Cowan

Relation of rooting response to age of tissue at the base of greenwood cuttings
door: A.E. Hitchcock en P.W. Zimmerman

Changes in leaves during the night
door: F.E. Denny

The origin of adventitious roots in cuttings of Portulaca Oleracea L. 
door: Mary H. Connard and P.W. Zimmerman

The Nursery Book (geplubiceerd in 1896)
A complete guide to the multiplication of plants
door: L.H. Bailey 

Oxygen requirement for root growth of cuttings in water 
door: P.W. Zimmerman

The response of roots to "Rootforming" substances
door: P.W. Zimmerman en A.E. Hitchcock

Microchemical studies of rooting and non-rooting rose cuttings
door: Margery C. Carlson

Several chemical growth substances which cause initiation of roots and other responses in plants
door: P.W. Zimmerman en Frank Wilcoxon

Tobacco as a test plant for comparing the effectiveness of preparations containing growth substances
door: A.E. Hitchcock