@article{Olevskii:1950:TSI,
author = {Olevski{\u\i}, M. N.},
title = {Triorthogonal systems in spaces of constant curvature in which
the equation $\Delta_{2} u+\lambda u=0$ allows a complete
separation of variables},
journal = {Mat. Sbornik N.S.},
volume = {27(69)},
number = {3},
year = {1950},
pages = {379–426},
language = {Russian},
note = {In Russian.},
mrclass = {36.0X},
mrnumber = {MR0038535 (12,415b)},
mrreviewer = {H. Busemann},
zblno = {0041.49802}}