J. Mäkinen, M. Bilker-Koivula, H. Ruotsalainen, V. Kaftan, N. Gusev, N. Korolev, V. Yushkin, R. Falk, W. Hoppe, O. Gitlein
Comparisons of six absolute gravimeters at four sites 2004–2007
http://geodesy-ngc.gcras.ru/fiches/Abs_comparisons_Makinen_et_al.pdf