Rakhmat Pramudita, Mohammad, Elvi Citraresmana, and Susi Yuliawati. “The Similarities of Thematic Progression in Zodiac Killer Letters”. International Journal of English Literature and Social Sciences (IJELS) 5, no. 5 (November 2, 2020). Accessed July 3, 2024. https://journal-repository.com/index.php/ijels/article/view/2654.