Original prints in the Boeckmann Center's Jose Guadalupe Posada Collection: Inquire at the Special Collection Reference Desk, Doheny Library, 2nd floor. https://archives.usc.edu/repositories/3/resources/513
On the Web: Jose Guadalupe Posada Collection, Harry Ransom Center, Univ. of Texas, Austin.
https://hrc.contentdm.oclc.org/cdm/landingpage/collection/p15878coll44#nav_top
Library of Congress: calaveras arroyo - https://www.loc.gov/pictures/search/?q=calaveras%20arroyo&loclr=blogflt