APA
Williams J. G., . (1967). A field guide to the national parks of East Africa. London: Collins.
Chicago
Williams John G, . 1967. A field guide to the national parks of East Africa. London: Collins.
Harvard
Williams J. G., . (1967). A field guide to the national parks of East Africa. London: Collins.
MLA
Williams John G, . A field guide to the national parks of East Africa. London: Collins. 1967.