Ignaz Marcel Gaugengigl art links 

Fine Arts Museums of San Francisco
Violin player seated on trunk, 1883
A Maiden Fair to See, 1881
Mischief, 1880

Ignaz Marcel Gaugengigl at the Metropolitan Museum of Art, New York City  
A Difficult Question (Une question difficile), 1883

Museum of Fine Arts, Boston  
Paintings collection online

Brooklyn Museum, New York City   NEW!

Brooklyn Museum/Luce Center for American Art, New York City
(Undocumented Feature: In many cases the raw JPG image is much larger than displayed on the screen)

Cleveland Museum of Art, Ohio

Dahesh Museum, New York City (Zoomable)
The Painter

Harvard University Art Museums, Massachusetts

Ignaz Marcel Gaugengigl at the Smithsonian American Art Museum, Washington D.C.

 
National Art Databases and Museum Inventories:

Smithsonian Institution Art Inventories
List of works nationwide from two sources: the Inventory of American Paintings Executed before 1914 and the Inventory of American Sculpture (only a few percent of listings have an accompanying image)

 

Ignaz Marcel Gaugengigl at The Athenaeum  

Wikimedia Commons Image Database  

 

Union List of Artist Names (Getty Museum)  
Reference sheet with basic information about the artist and pointers to other references.