Tradeskill Books to you can scribe
The one location you'll want to hit up in PoK for some Tradeskill Books is the small bank which is just east of the Guild Lobby. As you can see on my screen shot above I have four different NPCs marked. You'll want to buy all the books from them you can that you haven't already scribed.
I recommend the vendors in this order:
Scribe Zikett: Has the most books of all of them.
Blacksmith Gerta: Has about 8 different "Weapon Smithing" books for you.
Tailor Kujen: Much like Gerta he has some books with the suffix "Weapon Tailoring".
Culturist Devari: Has a lot of books for you just like Zikett.
Next up are a few locations that will have all duplicate books for you; assuming that you bought every single book off the previous four vendors. If you don't trust yourself and just want to check these vendors anyway, here's the list of them.
Katta Castrum Deluge: Artisan Antemm
Shard's Landing: Craftkeeper Bobus Tindlefoot
Argath: Bookseller Shoden (Use Find to reach Yaun who is standing nearby Bookseller Shoden)
After hitting up those vendors - or skipping them altogether you'll want to head to Sunrise Hills which is where we're going to find two more books to scribe. You can find Sunrise Hills just off the Guild Lobby. Once inside Sunrise Hills the first house you see after zoning in will have Garik Nogflop; the NPC we're here to buy from. He has two books.
After Garik we're going to head over to Aelisian Taliz in the Plane of Tranquility. This NPC has a few books you've already scribed as well as two that you haven't yet, Blessed Weapon Augmenting, Illustrious Weapon Augmenting by Jewelcrafting.
Image 1: Plane of Tranquility // Image 2: Brell's Rest
After we finish with Aelisian we're going to want to head over to Brell's Rest for the second to last set of books. The NPC we're looking for this time is called a Useful Automated Vendor. For me he had three different books available to scribe. He's found just outside the Shining City entrance which is a short run North from where you zone in.
Ceramic Weapon Ornament Sketchbook
Black Acrylia Weapon Ornament Sketchbook
The next stop on this educational trip is Abysmal Sea we're going to head over there and hit up a bunch of different merchants for some more books. To reach them you'll want to head to the Guild Lobby and speak to Magus Alaria whose found between the doors that lead to the Guild Hall and Grand Guild Hall.
Tell Magus Alaria that you want to travel to Nedaria's Landing and then once you're in Nedaria's Landing speak with Magus Wenla and tell him you want to travel to Abysmal Sea.
Once in Abysmal Sea you'll want to go out onto the first floor of the outside dock and over to where you see the light blue circle on my map location above. This is where you'll find a whole row of different Tradeskill NPCs (shown in the screen shot below). There's 4 on the east hand side of the building and one on the west.
I was only able to purchase 8 or so tradeskill books from these NPCs - the rest I had scribed. Also, only one NPC had any books for me - the single one that's standing on the opposite side of the building from where you see my screen shot.
In addition to the Tradeskill books in Abysmal Sea you also have a few quests that you can complete here for even more Tradeskill recipes. These will take up more than 30 minutes of your time which is why I have made an entirely different guide just for these quests. For more information on the Abysmal Sea GoD Tradeskill Quests follow my link to that guide.
After Abysmal Sea one of the last places we're going to go for more Tradeskill Recipes is Crescent Reach. This zone is very similar to Abysmal Sea in the sense that it has a butt load of NPCs for you to hit up as well as its own set of Tradeskill Quests for you to do. Luckily these Tradeskill quests aren't nearly as annoying as the Abysmal Sea ones. More on the quests in a bit.
Let's start with the different Tradeskill Books you can buy in Crescent Reach. The NPCs you need to buy the Tradeskill Books from are scattered throughout the city which makes finding them all really annoying. Luckily though every single one of them is on Find.
a tradeskill armor historian
a cultural tinkering historian
a cultural tailoring historian
a cultural smithing historian
a cultural discoveries historian
Note: All of these NPCs had duplicate books for me which likely means they will for you too if you've followed my guide word for word up until this point. Also don't forget to check the cultural tinkering historian even if you're not a Gnome!
Now, as for the Tradeskill Quests that come from Crescent Reach - as long as you have a skill level of 54 in that Tradeskill you'll be able to learn the recipes without having to do some super annoying quest to get them. Basically that means everyone reading this should be fine and can just run around hailing the NPCs and following their dialogue until it says 'recipes'.
Here's a map with every NPC's location marked on it that you need to talk to for recipes:
That's all we need to do in Crescent Reach. Now, we're off to the last and final stop on our long trip.... Thulisaur Island! Thulisaur Island is a zone in TDS (The Darkened Sea) expansion pack. You'll first need to be flagged for this zone which may be an issue for you if you've never done any TDS progression. This zone requires about 3/4 of all TDS progression to be done in order to access it.
Once here you'll need to purchase a Thaell Ew Ritual Armor book from Armorer Xochtli. His location is marked on the map below. Be careful running across Thulisaur Island to reach his location - there's plenty of enemies which will agro you without invisibility.
Additionally if you find yourself speaking to Armorer Xochtli and he doesn't sell anything - you're not alone! He didn't sell anything for me either even with max Kindly faction. If you don't have max Kindly faction there's still hope! In order to very quickly raise your reputation with the Thaell Ew all you need to do is purchase Loaf of Bread from a Thaell Ew Haggler that's ontop of the temple (in the central northern most part of the zone where all the lizard men are).
Once you have the Loaf of Breads (I just bought 1000) take them to any Thaell Ew Chef or Cook mob that's in the temples. Hand them all the bread and you'll get a ton of reputation with the Thaell Ew. That's all there is to raising your reputation with these guys. It caps out at Kindly from what I have seen and read.