1897 22 Feb. 3/2 Having adopted the custom of book-retention by the post-card system.
1965 20 Dec. 6/7 The early revolutionary ‘postcard’ system, when divorce was to be had for the asking.
2003 (Nexis) 6 Oct. 28 We have a postcard system where drivers can let us know if badgers and otters..are being squashed on the roads.