Good Question, but i can't tell you. Most of the models i posted are call themselves alternative Models and they're mostly private Persons, Photographers, Tailors, Crafters or Students etc. and not working for agencies. I "know" them via Photographers for Alternative Magazines or photographers i found at social media platforms like Facebook or Instagram. For example Aneta Pawska, a Photographer from poland, i really love the Pictures she shows on her FB-Page https://www.facebook.com/A.Pawska/ or "Gothic and Amazing" an Alternative Magazine who appears monthly and feature unknown and well known Models. I guess if you try Google with keywords like "alternative Model Agencies" you'll got a lot of hits. Alternative Models are not so specified like "normal Models" and have a wide range.