"PS2版「ef - a fairy tale of the two.」公式HP" [PS2 Edition Ef: A Fairy Tale of the Two Official Homepage] (in Japanese). Comfort. Archived from the original on October 18, 2012. Retrieved February 2, 2011.
"PS2版「ef - a fairy tale of the two.」公式HP" [PS2 Edition Ef: A Fairy Tale of the Two Official Homepage] (in Japanese). Comfort. Archived from the original on October 18, 2012. Retrieved February 2, 2011.
天使の日曜日 [Tenshi no Nichiyōbi] (in Japanese). Amazon.co.jp. Archived from the original on November 2, 2012. Retrieved February 2, 2011.