APA (7th ed.) Citation

Campbell, G., & Evans, I. O. (1969). The book of flags / by G. Campbell and I.O. Evans (6th ed.). O.U.P..

Chicago Style (17th ed.) Citation

Campbell, G., and I. O. Evans. The Book of Flags / by G. Campbell and I.O. Evans. 6th ed. O.U.P., 1969.

MLA (9th ed.) Citation

Campbell, G., and I. O. Evans. The Book of Flags / by G. Campbell and I.O. Evans. 6th ed. O.U.P., 1969.

Warning: These citations may not always be 100% accurate.