First of all, I'd like to disclose that I am extremely new at this whole "coin thing", so forgive me if this appears to be a silly question.
I have several baggies of Philippine coins that I am attempting to sort, and I've come to the 25 sentimos coins starting at 1975. The Standard Catalog of World Coins appears to be telling me that there are a few different mint marks for this denomination, but I can't locate where the mint marks are, at least on the 1975, 1976, and 1978 coins.
Can someone direct me to where I should be looking? Am I just blind? Thanks!