May I ask what you aren't able to find? It's worth noting that sometimes, exploring won't give you a book even when you don't have anything; you should find all the books of a certain level within the same set of areas.
I'm having the same issue with that 2nd Fire potion (even after spamming in the city to try n find it), as well as missing two of the ??? texts (I have the Song of Pholus, but not the other two, whatever they are)
