The semi-analytic planetary theory VSOP (French: Variations Séculaires des Orbites Planétaires, abbreviated as VSOP) was developed and is maintained (updating it with the results of the latest and most accurate measurements) by the scientists at the Bureau des Longitudes in Paris, France. The first version, VSOP82, computed only the orbital elements at any moment.

The VSOP 5 GHz AGN Survey I. Compilation and Observations
The VSOP 5 GHz Continuum Survey: The Prelaunch VLBA Observations
A Spectral Index Map from VSOP Observations of Markarian 501
VizieR Online Data Catalog: VSOP 5GHz AGN survey V. (Dodson+, 2008)
The Accuracy of ship's meteorological observations: results of the VSOP-NA
VSOP/Hv1 proton channels sustain calcium entry, neutrophil migration, and superoxide production by limiting cell depolarization and ...
Astrophysical Phenomena Revealed by Space VLBI, Proceedings of the VSOP Symposium, January 2000
The Accuracy of Voluntary Observing Ships' Meteorological Observations-Results of the VSOP-NA
New generation of monomer-stabilized very small superparamagnetic iron oxide particles (VSOP) as contrast medium for MR angiography:...
Preclinical characterization of monomer-stabilized very small superparamagnetic iron oxide particles (VSOP) as a blood pool contrast...