"Concerto" is a type of composition, so in the catalog, every instance of this piece will have that special library generic title added to help us find it: genre, medium, number, key -- concertos, piano, orchestra, K. 537, D major
A keyword search using the most important of those elements will find almost every instance of this concerto in the Library:
- composer - mozart
- title - concertos, piano, 537 [maybe even just 537]
- format - use drop downs or format words
Use what you know to search the catalog and look in the catalog record. In this case, "K. 537" is in the title.
Or use the online music encyclopedia from Oxford Music Online.