For the inventories and descriptions the MeMO project has used the sources that are named below in random order. For the floor slabs and tomb monuments these are:

• inventories from the past (mainly in Bloys van Treslong Prins, Belonje and Muschart)
• inventories and picture archives of the Foundation for Ecclesiastical Art and Artefacts Netherlands (SKKN) and the Cultural Heritage Agency of the Netherlands (RCE)
• research by MeMO
• new photographs (produced by MeMO in collaboration with the Cultural Heritage Agency of the Netherlands (RCE)
• photographs and information received from private persons, churches and companies
• publications

For the inventories and descriptions of the memorial pieces MeMO made use of the following:

• research by Truus van Bueren, colleagues and students as part of the Memoria project. In this context they researched memorial pieces for the area of the (Arch)diocese Utrecht for the period until circa 1630. One result of this project was the online database Representations of Medieval Memoria (2007-2009) (a.k.a. Memoria in Beeld).
• investigation of the objects and extensive analyses of the inventories carried out for the MeMO project or its predecessor, the Memoria project
• photographs of the Netherlands Institute for Art History (RKD) and the Foundation for Ecclesiastical Art and Artefacts Netherlands (SKKN)
• photographs from private persons and auction houses
• publications by other researchers

New insights have been incorporated in the descriptions, as well as corrections to the older literature. For instance, some slabs from the eleventh through the fourteenth century that are called sarcophagus lids in the literature are today recognised to be decorated sandstone slabs, unless either their long and tapering shape or the survival of the matching sarcophagus indicate that they did indeed serve as sarcophagus lids. Also, the flat stones that are found in the floors of churches are not necessarily floor slabs; they may also have covered tombs that have since been lost. This is the reason why the latter objects are treated as a single group in the database and are called Tomb slab or floor slab.