Gothic Cathedrals 

Catalogues Raisonnés
"All the works of an artist".  A scholar or a group of scholars documents every work of an artist's career.  Each work is pictured, with scholarly opinions, provenance (where the work has been), literature about the work, and spurious works (forgeries).  The first place to start when researching an artist or individual work. Not all artists have catalogues raisonnés.

Harpring, Patricia.  The Sienese Trecento painter Bartolo di Fredi. Rutherford : Fairleigh Dickinson University Press ; London ; Cranbury, NJ : Associated University Presses, c1993.  Lilly Library ND623.B28 H37 1993  
 
Bartolo, di Fredi, 1330-1410 -- Catalogues raisonnés.
Christian art and symbolism -- Italy -- Siena -- Medieval, 500-1500.

Corpora
Like a catalogue raisonné, only for a single kind of object.  One of the most famous corpora is that for medieval stain glass windows, Corpus vitrearum Medii Aevi.  An example is:

Ayers, Tim. The medieval stained glass of Wells Cathedral. Corpus vitrearum Medii Aevi.  Great Britain, 4.
Oxford : Published for the British Academy by Oxford University Press, 2004.  Lilly Library NK5344.W47 A94 2004

Corpus vitrearum Medii Aevi. Great Britain ; v. 4
Glass painting and staining, Medieval -- England -- Wells.

Permanent Holdings Catalogs (of museums)

Detailed catalogs of a period or genre of art in a particular museum.  Like a catalogue raisonné, it will contain a collection of scholar's opinion on an object, conservation reports, provenance and literature (written about it).  If you know of the location of a work of art, check for permanent holdings catalogs.

Cloisters (Museum)   Medieval monuments at the Cloisters as they were and as they are. By James Rorimer.   Rev. ed. by Katherine Serrell Rorimer. New York, Metropolitan Museum of Art, 1972 Lilly Library 708.1 M594CLMa

Art, Medieval.