Ok, I've read that the locations of tomes are pretty random, but I'd like to know just how random are they.
Are they placed completely random anywhere in Gael Serran? Or do they always appear in the same general area (for instance in the Serpent Temple, Boogre Pits, Skull Isle...) and are just placed randomly inside each area?

The reason I'm asking is, I've read several people saying they've found one of the Tomes inside The Serpent Temple and I found nothing of the sort in there, even though I've searched it pretty thoroughly (I hope). On the other hand, I've just finished the Boogre Pit and I found the Tome of Wind in there.

So, am I gonna have to go looking through the Serpent Temple again or can I hope to find the other three Tomes in the next areas? Any info would be appreciated.

I found the tome of fire in the serpent temple, in the undertemple treasury, that's the room with a gate that needs the skull key just past the place where you kill the naga. You don't get the skull key until later so you may have forgotten to go back.

The tome of water should be in the sunken city in the lost sea and the tome of earth is in Cet's pyramid in the isle of sands.

I'm not so sure that the special objects are placed randomly, in my games they seem to be pretty much in the same place as reported by others.