CHRISTIE, A. THE SECRET ADVERSARY.
芝加哥风格引文CHRISTIE, AGATHA. THE SECRET ADVERSARY.
MLA引文CHRISTIE, AGATHA. THE SECRET ADVERSARY.
警告：这些引文格式不一定是100％准确.
APA引文
CHRISTIE, A. THE SECRET ADVERSARY.
芝加哥风格引文CHRISTIE, AGATHA. THE SECRET ADVERSARY.
MLA引文CHRISTIE, AGATHA. THE SECRET ADVERSARY.