A paradigm change in scholarly communication is underway. Supporting Open Science, an effort to make scientific research data accessible to all interested parties by openly publishing research and encouraging others to do the same thereby making it easier to communicate scientific knowledge, is a part of the change that has become increasingly important for (digital) libraries. Digital libraries are able to play a significant role in enabling Open Science by facilitating data sharing, discovery and re-use. Data citation is often mentioned as one incentive for data sharing, and therefore enabling data citation is a crucial feature of research data services. In this article we present a case study of data citation services for the High-Energy Physics (HEP) community using digital library technology. Our example shows how the concept of data citation is implemented for the complete research workflow, covering data production, publishing, citation and tracking of data reuse. We also describe challenges faced, and distil lessons learnt for infrastructure providers and scholarly communication stakeholders across disciplines.