I'm not entirely sure why you think this isn't significant.  The whole crux of the disagreement was on independence for Lithuania, and the anti-Soviet leaders really didn't have the power to achieve that with anything but diplomacy and referenda (again, not saying that what they did was legal or illegal, but pratically speaking).  I'm not sure about your 'biased and nationalistic' books, but a few seconds of searching brought me a New York Times front page article from 5/17/90 titled "EVOLUTION IN EUROPE; LITHUANIA AGREES TO SUSPEND LAWS ON INDEPENDENCE."  I know about the rule regarding individual research, but I did a term paper in college about this that I'm going to try to dig up and use the bibliography.  If I remember, there was quite a bit on JSTOR so if you've got access to it you should check it out.  I think it's relevant to the recent Ukraine-Russia dispute because it shows the significant power that Russia/USSR can wield with the threat of an energy embargo.