于健. (2003). 攻克英语: College English 4. 机械工业出版社.
Chicago Style (17th ed.) Citation于健. 攻克英语: College English 4. 机械工业出版社, 2003.
MLA (8th ed.) Citation于健. 攻克英语: College English 4. 机械工业出版社, 2003.
Advarsel: Disse citationer er muligvist ikke 100% nøjagtige.