|Breitkopf & Härtel, Leipzig (Pub.)||Concertos|
For large works, one work is the equivalent of one opus. Shorter works
were published in sets. Thus Op. 18, a set of six quartets, contains
Nos. 1-6, but the Violin Concerto, Op. 61, has no further designation.
Some works by Beethoven have acquired nicknames, but in general (e.g.,
the "Moonlight" Sonata, the "Emperor" Concerto, the "Rasoumovsky"
quartets) these are later accretions and we have not gone out of our
way to include them.