Below are some websites that I recommend

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First Leissring Fine Art Website: includes history and reconstruction of McDonald Mansion
Major site for JC Leissring Fine Art; Many artists included.

Jacques Villon Etchings JCLFA
I have the largest collection of Jacques Villon works on paper existing. This site includes details of each of the images in the collection of 358 works. The collection is for sale.
Under the search "Leissring" you can find most of the 23 books I have published.

Annex Galleries
Finest collection known to me, of European and American art works, predominantly works on paper. Extremely knowledgeable.