@book{gledocs_11858_00-1735-0000-0001-3278-C,
author = {Helm, Achim},
title = {Ground-based GPS altimetry with the L1 OpenGPS receiver using carrier phase delay observations of reflected GPS signals},
year = {2008},
publisher = {GFZ, Helmholtz-Zentrum, Potsdam},

note = { \url {http://hdl.handle.net/11858/00-1735-0000-0001-3278-C}},
}