Williams, S. (1999). Focus on vocabulary. Cornelsen & Oxford.
Chicago-Zitierstil (17. Ausg.)Williams, Steve. Focus on Vocabulary. Berlin: Cornelsen & Oxford, 1999.
MLA-Zitierstil (8. Ausg.)Williams, Steve. Focus on Vocabulary. Cornelsen & Oxford, 1999.
警告：这些引文格式不一定是100％准确.