Context-aware links between electronic health records (EHRs) and online knowledge resources, commonly called "infobuttons" are being used increasingly as part of EHR "meaningful use" requirements. While an HL7 standard exists for specifying how the links should be constructed, there is no guidance on what links to construct. Collectively, the authors manage four infobutton systems that serve 16 institutions. The purpose of this paper is to publish our experience with linking various resources and specifying particular criteria that can be used by infobutton managers to select resources that are most relevant for a given situation. This experience can be used directly by those wishing to customize their own EHRs, for example by using the OpenInfobutton infobutton manager and its configuration tool, the Librarian Infobutton Tailoring Environment.