Michael Watkins; Kevin Wallace, C. N. 7. CCNA Security Official Exam Certification Guide (Exam 640-553) (1.). Pearson India.
芝加哥风格引文Michael Watkins; Kevin Wallace, CCIE No. 7945. CCNA Security Official Exam Certification Guide (Exam 640-553). 1. Pearson India.
MLA引文Michael Watkins; Kevin Wallace, CCIE No. 7945. CCNA Security Official Exam Certification Guide (Exam 640-553). 1. Pearson India.
警告：这些引文格式不一定是100％准确.