Recent Knowledge Graphs (KGs) like Wikidata and YAGO are often constructed by incorporating knowledge from semi-structured heterogeneous data resources such as Wikipedia. However, despite their large amount of knowledge, these graphs are still incomplete. In this paper, we posit that Online Social Networks (OSNs) can become prominent data resources comprising abundant knowledge about real-world entities. An entity on an OSN is represented by a profile; the link to this profile is called a social link. In this paper, we propose a KG refinement method for adding missing knowledge to a KG, i.e., social links. We target specific entity types, in the scientific community, such as researchers. Our approach uses both scholarly data resources and existing KG for building knowledge bases. Then, it matches this knowledge with OSNs to detect the corresponding social link(s) for a specific entity. It uses a novel matching algorithm, in combination with supervised and unsupervised learning methods. We empirically validate that our system is able to detect a large number of social links with high confidence.