In this paper we present reflections and recommendations concerning the conversion of library metadata into Linked Data. We will briefly describe the different data models that exist for this purpose and argue their strengths and weaknesses with a special focus on the entification issue, before illustrating this problem with the description of three different ongoing projects. As will be outlined afterwards, it is essential to distinguish at the start of a project between data-driven or user-driven design approaches. As an alternative, the realization of a Linked Data project for bibliographical data might also lead to a hybrid approach were the design process shifts reciprocally between the analysis of the data and the user needs.