X + YY: Formel des Bösen
- Jaar: 1970
- Land: Germany
- Genre: Crime, Thriller
- Studio: Brünnstein-Film
- Sleutelwoord: exploitation, playboy, serial killer, hormones
- Direkteur: Pavle Jovic, Teja Piegeler
- Gooi: Ljubiša Samardžić, Kai Fischer, Miloje 'Mića' Orlović, Albert Hehn, Leonina Pavlović, Stefan Zessner
