Medium: color aquatint. Collection: National Gallery of Art. Pierre-Michel Alix after Jean-François Garnerey after Louis Michel Van Loo, Helvetius, NGA 43334
Author: Pierre-Michel Alix (1762–1817) After Jean-François Garneray (1755–1837) After Louis-Michel van Loo (1707–1771)Source: https://commons.wikimedia.org/