I have a stock certificate issued 9/26/1972 for Sterling Mining Corporate. There is a state of NV seal embossed. There is not CUSIP number. It lists the share amount in the right corner and two digit number in red on the left corner (not identified as a CUSIP). It is signed by the company treasurer and president (although full names are hard to read). I have tried searching the corporation records for NV, nothing comes up. I’ve searched Google high and low. All I can find is a company called Sterling Mining Company from Idaho on all these searches. Does anyone have any advice on how to further investigate this without paying a broker?