美國專利委員簽發的專利證書Patent letter, from the commissioner of Patents, USA
1969年11月11日
Written, 'a request for the grant of a patent has been made by Lau, Chun Leung and Lau, Chi Leung, both Chinese and both of 24 Pine Street, 1st Floor, Tai Kok Tsui, Kowloon in the Colony of Hong Kong for the sole use and advantage of an invention for calendar clock mechanism.'