18th-19th Century French oil pastel drawing identification

Hello forum group, I recently acquired a very old drawing/sketch, it is done with an oil stick or oil pastel the old type mixed with wax or animal fat, It is very hard to rub off and does feel waxy/oily, this mat be a very important artwork and im very curious if anyone could tell me some resources that would help identify the artist, thank you for your time. I do not see where i can post a pic or i would