These images are made available under the Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 License. You may copy and redistribute the
material in any medium or format but must give appropriate credit, provide a link to the
license, and indicate if changes were made. You may not use the images for commercial
purposes. If you remix, transform, or build upon the material, you may not distribute the
The images, apart from restricted files in Series 2, are open for research use. Restricted
images in Series 2 are restricted 60 years from date of creation.