WANG Zhi, LIU Shi-rong, SUN Peng-sen, GUO Zhi-hua, ZHOU Lian-di. The Variability of Vegetation Beginning Date of Greenness Period in Spring in the North-South Transect of Eastern China Based on NOAA NDVI[J]. Spectroscopy and Spectral Analysis, 2010, 30(10): 2758