Public galleries are mentioned first, then private collections, and
churches last. The principal public gallery is always understood after
the simple mention of a city or town. Thus, Paris means Paris, Louvre,
London means London, National Gallery, etc.
An interrogation point after the number or title of a picture indicates
that its attribution to the given painter is doubtful.
Distinctly early or late works are marked E. or L.
It need scarcely be said that the attributions here given are not based
on official catalogues, and are often at variance with them.