Nevertheless, even research limited to extant works may still tell us more about medieval drama. The number of extant tropes has more than doubled with Donovan's study. Works in the vernacular are becoming more accessible. Scholars are increasingly aware that there is a great deal more work to be done with regards to finding more examples of medieval drama. For example, Donovan only consulted 5 customaries from Castile in his study and four of them contained tropes.
More research is necessary to exhume further examples of medieval liturgical drama.
In the meantime, cathedral libraries are not our only source of information. The number of chronicles, church decrees, traveler's accounts and other non-literary documents that contain references to medieval drama is impressive. More importantly, in many cases the quality of the descriptions of liturgical and court drama is so great that we actually learn as much reading a description as we would reading the play itself. Not all documents that mention plays or spectacle can be considered to be proof that drama existed in Medieval Spain. This famous section prohibits the clergy from participating in plays during the Mass that distract from the service, but permits such plays that inspire devotion.