There are many sources about Van Gogh and art in general on the 5th floor regular stacks and in special collections on the 6th floor.
Vincent Van Gogh : the letters : the complete illustrated and annotated edition / edited by Leo Jansen, Jans Luijten and Nienke Bakker. N6953.G63.A3 2009 Limited Access
Vincent van Gogh a Auveres: his last days/Wouter van der Veen, Peter Knapp. ND653.G7.V4513 2010
Vincent Van Gogh and Expressionism/Jill Lloyd. ND653.G7.A4 2006
1900 Art At the Crossroads /Rosenblum, Stevens and Dumas. N6493.R67 2000