Peter D.Riley. (2019). Cambridge Checkpoint Science Student's Book 1 (2nd.). Hodder Education; Stu New edition (2011-05-27).
Čikaški stil citiranja (17. izdanje)Peter D.Riley. Cambridge Checkpoint Science Student's Book 1. 2nd. Hodder Education; Stu New edition (2011-05-27), 2019.
MLA način citiranja (9. izdanje)Peter D.Riley. Cambridge Checkpoint Science Student's Book 1. 2nd. Hodder Education; Stu New edition (2011-05-27), 2019.
Upozorenje: Ovi citati možda nisu uvijek 100% točni.