The very best silvia titles seem to be her early european ones. There hard to get hold of though as most titles arent in English, & she's made films all over the world.
Her Private movies are also very good. Call Girl is spose to be one of her best. Also check out - Devoured, Dangerous Things 1&2, The Acadamy, & Xtreme Desires.
A Euro company called Bose Madchen ?, made some very good films with her quite early on, I dont know if these are out on DVD though.

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