6David Sugar. Susceptibility of Red Fruited Pear Cultivars to Fire Blight [J] .Acta. Horticulturae, 1987 (217): 285-287.
7Maria Claudia Dussi,David Sugar,Anita Nina Azarenko, et al.Righetti Colorimetric Charactrization of Red Pear Cultivars [J] .Fruit Varieties Journal , 1997, 51 (1) :39-43.
8Maria Claudia Dussi,David Sugar and Ronald E.Wrolstad Characterizing and Quantifying Anthocyanins in Red Pears and the Effect of Light Quality on Fruit Color [J] .Amer. Soc. Hort. Sci., 1995, 120 (5) :785-789.
9David Sugar and Porter B. Lombard Harvest Sequence, Storage Life, and Marketing Periods for Red Pear Cultivars in the Pacific Northwest Region of the United States [J] .Acta. Horticulturae , 1998 (256): 231-233.
