Trademarks by Mikiko Ponczeck.
Trademark documents and explanatory materials from WIPO. WIPO administers the Madrid System, which allows persons and entities to register their marks so that they can be protected in multiple countries.
A sampling of trademark offices with organizations and different countries.
A sampling of international databases set up for trademark searching.
It is a lot easier to search databases nowadays thanks to online translators. Still, these helpful programs are not perfect. Classification systems organize marks by what they are not what they are called. So we can use these to search for marks in different countries even if we do not understand the local language.
Global competition and trade requires a local knowledge of how countries might deal with different marks and mark disputes. Fortunately, there are several secondary sources which give you an international "lay of the land."