In the "old days" this was what had to be done manually. I simply printed the reference list (one-sided print) and went through the text and checked the references I passed in the text and checked the corresponding one in the reference list. This would take maybe 20-30 minutes(?). It is clear that this is easier to do on paper than on screen but it is a very safe way to do the checking. In the end you will (hopefully not) end up with references missing ticks in either the text or the list.
