1. Conservation Department, The Art Institute of Chicago, 111 South Michigan Avenue, Chicago, Illinois 60603
2. Department of Scientific Research, The Metropolitan Museum of Art, 1000 Fifth Avenue, New York, New York 10028
3. Department of Chemistry and Center for Analysis of Structures and Interfaces, The City University of New York, Convent Avenue at 138th Street, New York, New York 10031
4. Chemistry Department, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60203