http://classicphoto.co.kr/cp/home/library.php?mid=4&r=view&uid=3364
http://classicphoto.co.kr/cp/home/library.php?mid=4&r=view&uid=3363
원본은 classicphoto.co.kr 의 Library 에 있습니다.
http://www.leica-gallery.org/leica_m/leica12_1_body.htm
http://www.leica-gallery.org/leica_m/leica12_2_lense.htm
원본은 http://www.leica-gallery.org/index.html 에 있습니다.
2024. 01. 25 업데이트
https://www.cameraquest.com/mtype.htm
https://www.cameraquest.com/ltmnum.htm
https://www.kenrockwell.com/leica/lens-serial-numbers.htm
https://wiki.l-camera-forum.com/leica-wiki.en/index.php/Serial_Numbers_Leica_Cameras
