TY  - JOUR 
T1  - USING SURFACE FITTING AND BUFFER ANALYSIS TO ESTIMATE REGIONAL GEOIDAL UNDULATION
JO  - Boletim de Ciências Geodésicas
A1  - NING, FANG-SHII
SN  - 1982-2170
UL  - 10.1590/S1982-21702015000300035
VL  - 21 
Y1  - 2015
PB  - Brasil 
ER  -