APA
Donaldson J., . (2007). Pen-pals. Oxford: Oxford University Press.
Chicago
Donaldson Julia, . 2007. Pen-pals. Oxford: Oxford University Press.
Harvard
Donaldson J., . (2007). Pen-pals. Oxford: Oxford University Press.
MLA
Donaldson Julia, . Pen-pals. Oxford: Oxford University Press. 2007.