Ok, here is the new list, added some traders and it´s easier to read now...
When books marked with * it means they are in area where you need reputatation to get to.
Somewhere I wrote like "Aidan(Monastery)-4" it doesn´t means that he gives you 4 tablets, it means that you can get 4x5=20 INT from it, but it might be 1 tablet that gives 20 INT at once...
And don´t forget to save before talking to merchants, because first time you talk to them they generate inventory and it might be possible that they wont have tablets at all. However I couldn´t buy more that 3 tablets from each...
MYRTANA
Ardea
-Books:INT,ALC
Reddock
-Books:ALC
Cape Dun
-Books: ALC, INT*
-Traders: Deckard
Montera
-Millstone*
-Traders:Basir
Silden
-Books:INT*, ALC
-Traders:Temmy
Geldern
-Books:3xALC, 2xINT*, 3xALC*,
-Traders:Jared, Renwik, Mirzo, Hamil
-Millstone
-Geldern Arena: 3
-Geldern Mine(with minecrawlers): 2
Trelis
-Books: ALC, INT
-Traders: Khabir
Nemora
Okara
Faring
-Millstone*
-Books(need 75 rep with orcs):3xALC**, 2xINT**
Gotha
-Traders: Narkan
-Books: INT(inside castle)
Vengard
-Millstonex4(these are outside castle)
-Books(these are outside castle):ALC
-Books(inside castle): INT, ALCx2
VARANT
Braga
-Books:INT
one more INT book in nomad camp to the west
Ben Erai
-Books:ALC
Lago
Bakaresh
Mora Sul
-Traders: Ilja, Faesul
Al Shedim
-About 10 tablets lying around
Ishtar
-Books(need 75 rep with hashishin):INT, ALC
NORDMAR
Monastery
-Books: 2xALC, INT
Furnace
-Millstonex2(you will have to kill lots of orcs before you can get there)
Xardas´ tower
-Books: INT, ALC
NPCs that can give you stones with or without quest
Aidan(Monastery)-4, you have to bring him druid stone first
Lester(Al Shedim)-2
Myxir(Al Shedim)-2
Medrarion(west of Mora Sul)-2