RT Journal Article T1 On an oblique boundary value problem related to the Backus problem in Geodesy A1 Díaz Díaz, Jesús Ildefonso A1 Díaz Díaz, Gregorio A1 Otero Juez, Jesus AB We show the existence and uniqueness of a viscosity solution for an oblique nonlinear problem suggested by the study of the Backus problem on the determination of the external gravitational potential of the Earth from surface measurements of the modulus of the gravity force field. PB Amsterdam Elsevier Science 2000 SN 1468-1218 YR 2006 FD 2006-04 LK https://hdl.handle.net/20.500.14352/49967 UL https://hdl.handle.net/20.500.14352/49967 LA eng NO DGISGPI (Spain). NO EC DS Docta Complutense RD 26 sept 2025