The trip requires a certain amount of research to be carried out before setting off.
You can download free cityguides in pdf format from in your pocket. Since they are for free, there are obviously lots of advertisements included but otherwise they are not bad at all, in particular if its a city you just pass through and don't want to spend money on a guide book. Also, when you left the place you can simply recycle them and don't need to carry them along. I always have a hard time letting go of real guidebooks. Inyourpocket guides are available for Minsk and Moscow (and many other cities).
For the Trans-Siberian Railway:
IMHO the two best guidebooks covering the railway are Bryan Thomas and the LP edition of the track.
Moscow and Beijing mar the beginning and the end and deserve some more days and more extensive coverage.
For Shanghai I trust my personal city guide Shanghai-Sändi to lead me to the darkest alleyways and seediest etablissements.
The LP Mongolian country guide was purchased to do some pre-trip research but given the time I will get to spend there and the meetings with local vs. the weight to carry it, it will most likely stay home. sorry...
The small world atlas is a little book I tend to have in my bag which comes in handy if you meet someone and you want to show them which part of the world you're from, where you've been to, where you're going and to plan future trips.