We planned to travel this year trough Serbia, with car and tent, there fore we need a good detailed automap from Serbia. Who can advise me and know an adress where to buy.

Most gas stations in Serbia sell it and they are pretty good.

First try a website version on www.viamichelin.com to plan your route.

Also try this link... http://www.mfa.gov.yu/Srpski/Facts/Map/index_s.html

You can click on squares to enlarge them... Maybe it's not a printable resolution, but it could help.

And I'm sure that you can buy a map of Serbia on any gas station in Serbia and neighbour countries.  

http://c.imagehost.org/view/0939/AutoKartaSrbije_www_planacafe_com.jpg