[Kazakami Shun] Active Renai Houteishiki Official Visual Book

[Hiyoshi Hana] Kare to Imouto no Houteishiki | The Equation of Him and His Little Sister (COMIC Megastore 2012-08) [English] [The Lusty Lady Project]

[Azuki Kurenai] Midara no Houteishiki - The equation of the Immoral Ch. 9 [English] [SaHa]

[Carn] Natsu x Umi = Kiken no Houteishiki | Summer x Beach = Dangerous Equation (Shinzui SUMMER Ver. Vol. 2) [English] [Rage Manga] [Decensored]

[Momonga Club (Hayashibara Hikari)] Shoujo no Houteishiki - Girls of Equation [Digital]

[Azuki Kurenai] Midara no Houteishiki - The equation of the Immoral Ch. 1-2 [English] [hen-toy]

(C59) [Tomoyosama (Kayama Akihiro, Ozawa Hiroe)] Tomoyo No Yasashii Houteishiki (Cardcaptor Sakura)

[Anthology] Kimusume Kanojo no Hatsujou Houteishiki [Digital]

[Sena Youtarou] Kannou no Hirusagari | A Sensual Early Afternoon (Kannou no Houteishiki) [English] [QBtranslations]

[Uruudoshi (Uru)] Seiai no Houteishiki (30-sai no Hoken Taiiku)

[ITOYOKO] Kichiku Houteishiki - Equation of brutal person

[Fumizuki Kou] Koi suru Houteishiki

(C74) [Momonga Club (Hayashibara Hikari)] Shoujo no Houteishiki - Girls of Equation

[Azuki Kurenai] Midara no Houteishiki: The Equation of the Immoral

[Yuiga Naoha] 4P Houteishiki (COMIC P Flirt Vol.10 2011-04)

[Hiyoshi Hana] Neko to Watashi no Houteishiki | The Equation of the Cat and Me (COMIC Megastore 2012-02) [English] [The Lusty Lady Project]

Chigiri to Musubi no Houteishiki - Equation of Chigiri & Musubi

Koi no Riron Ai no Houteishiki

Kimusume Kanojo no Hatsujou Houteishiki

Kirei na Onna to H no Houteishiki

Sprechchor to Houteishiki | Chorus and Formula

Kirei na Hito to H no Houteishiki

Neji to Nejiana no Houteishiki

Midara no Houteishiki - The Equation of the Immoral Kanzenban

Nurume no Houteishiki.

Kannou no Houteishiki

Atatame no houteishiki

Rina-chan Renai Houteishiki

Eien no Houteishiki - Eternal Equation Chapter: 1

Neji to Nejiana no Houteishiki

Rina-chan Renai Houteishiki

Pain Jakase no Aishita Renketsu Houteishiki

Kannou no Houteishiki (decensored)

Midara no Houteishiki

Chigiri to Musubi no Houteishiki | 契與結的方程式