An example of a flexible polyhedron with nonconstant volume in the spherical space. Alexandrov, Victor — 1997 Beiträge zur Algebra und Geometrie
Sufficient conditions for the extendibility of an n -th order flex of polyhedra. Alexandrov, Victor — 1998 Beiträge zur Algebra und Geometrie
On the total mean curvature of a nonrigid surface. Alexandrov, Victor A. — 2009 Sibirskij Matematicheskij Zhurnal