The scores of the Bartók concerto, available for download, are edited by Lars Tomter.

Changes and adjustments to the manuscript of Bartók, must be compatible with the Serly score for those who play Serly.

A few remarks by Lars Tomter for those who consider his version of Bartók's viola concerto:

First, there are a couple of misprints in the solo score that has been out, you might have discovered. Please use updated version.
2nd movement:
Bar 9: top note C-sharp
Bar 42: Forte from upbeat
Bar 103: last note G Sharp

The solo part was to a big extent completed by Bartók, as opposed to the orchestra part.
This means that the actual notes are basically the same in mine and Péter Bartók's solo parts.
The big difference is the placing of the section that traditionally has been set between 1st and 2nd movement, which I have placed in the third movement bar 221 to 234 .
Leading up to that is a section that has not been used in other versions.
The orchestra line of this section bars 204 to 220 is complete by Bartók. The solo line he wrote first four bars, 204- 207, this has been completed by me.
Otherwise the main differences of my version to others are in the orchestra score.
Bartók left hardly any articulation or dynamic marks, also not in the solo part.
My contributions in this respect are to be seen as suggestions, all performers should make their own choices.