https://www.listia.com/auction/35915530-2006-51st-unminted-state-proof-dc-state

http://www.treasurenet.com/forums/coins/485650-999-quarter-copy.html

https://forums.collectors.com/discussion/960035/2004-dated-washington-dc-quarter-scans-added

https://www.cointalk.com/threads/odd-washington-d-c-quarter-copy-cool-reverse-design.122956/