Gravil, R. (2007). Existentialism. Humanities-Ebooks.
芝加哥风格引文Gravil, Richard. Existentialism. Tirril [England]: Humanities-Ebooks, 2007.
MLA引文Gravil, Richard. Existentialism. Humanities-Ebooks, 2007.
警告：这些引文格式不一定是100％准确.
APA引文