X + YY: Formel des Bösen
- Annu: 1970
- Paese: Germany
- Genre: Crime, Thriller
- Studio: Brünnstein-Film
- Parolla chjave: exploitation, playboy, serial killer, hormones
- Direttore: Pavle Jovic, Teja Piegeler
- Cast: Ljubiša Samardžić, Kai Fischer, Miloje 'Mića' Orlović, Albert Hehn, Leonina Pavlović, Stefan Zessner
