APA
Keck D., . (1998). Angels & angelology in the middle ages. Oxford: Oxford University Press.
Chicago
Keck David, . 1998. Angels & angelology in the middle ages. Oxford: Oxford University Press.
Harvard
Keck D., . (1998). Angels & angelology in the middle ages. Oxford: Oxford University Press.
MLA
Keck David, . Angels & angelology in the middle ages. Oxford: Oxford University Press. 1998.