Online collections of historic stereoviews

Library of Congress Stereograph Cards https://www.loc.gov/pictures/collection/stereo/ The Great War in 3D http://www.greatwarin3d.org/ New York Public Library Stereogranimator http://stereo.nypl.org/ Keystone-Mast Collection http://ucr.emuseum.com/collectionoverview/3631#sthash.awfsQlo8.dpbs World of Stereoviews http://www.worldofstereoviews.com/