some cases the work is presented with key word search functionality, and in other cases with high-quality digital scans in color -a laudable attempt to embody the original book enhancing the use of these digital primary sources. Furthermore, portals such as the PRDL, an aggregated website, greatly improve the accessibility, and foster a guided use of the various digital resources of Calvin's work such as commentaries, sermons, doctrine, polemic, catechetical / liturgical, and correspondence (PRDL 2011). 2. SUBSCRIPTION-BASED: DLCPT, EEBO AND IRRThe DLCPT offers more than sixty selected works of Calvin, which are fully and advanced searchable, such as single term and phrase search, proximity searching in the same sentence or in the same paragraph on selected parts and the entire work or collective Calvin corpus; each work containing page images of the original letterpress edition connected to the searchable digital edition. Search results are presented in context or line by line, and in page order, and can be viewed by individual page, paragraph or section. The accuracy of the search result is highly precise, and offers the user the option to view the corresponding page image of the printed work in a separate window. Page images of printed works, though with various image quality and limited search capabilities is the core of the more than fifty English works of Calvin offered by EEBO. The Calvini Opera (CO) developed by IRR as fully searchable PDF's on compact disc formed the basis of a recent and promising initiative - the combination of a fully and advanced searchable CO integrated with corresponding page image, like the DLCPT, and whereby specific works can be linked to digital editions that are available as open access documents. The user is then able to view the search result of, for example, the Interim Adultero-Germanum, as digital text, text image of the CO and text image of the 1549 edition available through BNF (Calvin 1549). Furthermore, IRR envisions that the CO is cross-searchable with other series of the Corpus Reformatorum, and other works of the sixteenth-century Reformation.These works of Calvin, then, differentiate themselves primarily in their advance search capabilities and the level of precision of search results from the current open-access publications, as well as their ability to view the digitally formatted text with the corresponding page image. In this way, EEBO offers download functionality for licensed users, which option is currently not available by DLCPT and IRR.This succinct survey shows the various and diverse digital primary sources of the works of this 16th-century Protestant Reformer. Although the majority of the commercially available digital works are still available only through sometimes cost-prohibitive user licensing, a more recent trend shows that open-access initiatives such as GB, IA, and e-rara make identical editions available. For example, the 1540 Commentarri in Epistolam Pauli as Romanos, previously available digitally through the DLCPT, is now freely accessible through IA (Calvin 1540). Other publications, such as the Defensio othodoxa fidei de sacra Trinitate, are now available through the DLCPT, BNF and GB.5 Here, two observations are in order: first the search limitation of the open