APA

clarke a. c., . (2009). tales of ten worlds. london: macmillan.

Chicago

clarke arthur c, . 2009. tales of ten worlds. london: macmillan.

Harvard

clarke a. c., . (2009). tales of ten worlds. london: macmillan.

MLA

clarke arthur c, . tales of ten worlds. london: macmillan. 2009.