The variation I'm talking about is:
- e4 c6
- d4 d5
- exd5 cxd5
- Bd3 Nc6
- c3 g6!? .
[FEN ""]
- e4 c6 2. d4 d5 3. exd5 cxd5 4. Bd3 Nc6 5. c3 g6!?
I found it in an old book about the Exchange Caro-Kann but it's written without ideas, only a list of moves and for me it's not so useful. In general, I've found out by viewing that list of moves that it could be a sort of system: Black wants ... Bg7, ... Nh6, ... f6 followed in the future by ... e5 if White allows it, but I tried playing it on lichess and my execution was really bad; so I'm interested in the opening and curious about resources.