Design Patterns Learning Sources

I've been thinking about learning DP on my own before my uni course about them but I don't know what's the best source for that.Some famous books about them are either in Java which I don't know or theoretical which I've heard that many don't understand.What do you think it's the best way to learn them? I would prefer either book or some online course (free) in C# but if that's not possible I could learn Java