Our area of interests is focused on geo-based recommendation systems which exploit relations between users in social networks. In order to evaluate, adjust and extend our initial idea we performed a survey looking for both commercial products and academic researchers related to these topics. However, this post is devoted entirely to academic works. In our investigation we focused, first of all, on location-based recommendation systems on top of social networks, suggestion algorithms exploiting social network relations and the level of trust in recommendation systems and trust factors. Furthermore, we considered materials about the level of anonymity and privacy issues in social networks, legal issues with user-generated content, social and economic impact of recommendation systems.