Shading linked objects

posted to: Shading the Room

I got a problem with these linked objects. Some of them, like the Skateboard won't find their image textures. I guess these were not included in the download files. Now i'm trying to edit the materials of these objects but i can't access them. Even if I unlink these objects i still can't edit the objects. And i don't want to go manually into every model file to fix the materials, since i can't use the edit linked library addon with Version 2.79

What can i do now?