^Hayes, James (2006). The great difference: Hong Kong's New Territories and its people, 1898-2004. Hong Kong University Press. p. 208. ISBN 9789622097940.: "Cargo junks of the type still known as kai to or "local ferry" had long plied between NT ports, Hong Kong, and places in the Canton Delta: see e.g. the list of ports in the papers at GN 170 in HKGG, 17 November 1866. They were sometimes operated in the public interest and paid for from public funds."
^"Transport Department - Kaito Ferry Service Details". www.td.gov.hk. Retrieved 5 May 2023.