Page 1 and 2
Page one can be found if from the beginning you go either east or west (they join later) and then go east. It says to use Hawk/Barrager/Bullseye againt Degasser.
Page two can be found East from the second portal, Armored Army KB Tactical Area. It refers to using a Degasser against Patriot.
Page 3 and 4
Page three can be found when you first encounter Degasser. It says to use a Ga-Boi against Worthog.
Page four is found in the only area you will find Ambush, defeat all of them and it will apear. It refers to using Hawk, Degasser and Ambush against Gargantua.
Page 5 and 6
Page five and six can be found by going North from the portal, Avalon Fortress. It's found inside a memory stone. It refers to the fight against the Folklore of the realm. First use Ga-Boi against the oil tank on it's back until it explodes. Then use Gargantua to break the armor on it's legs. And when it's down and showing it's mouth attack the mouth with Degasser or Worthog.
Its important to note Keats can only find 3 pages out of 6 at this stage in the game, they are pages 1,4 and 5. There is another picture book page but you will notice in the KB Territory (furthest exit North West of the second portal) that this area is blocked by an ice crystal and so must be revisited further into the game [this is where a memory page is].
Upon entering the area where the second portal is [marked as KB Territory] a route directly east should be very close to that portal, taking it will lead to an area filled with Ga-dearg and hawks, kill them as you must.
Upon the elevated hillside (it would be facing you as you entered the area) there's a crystal 'memory...' break it to find page 1, showing three hawks fleeing.
Page Four; from the second teleport head directly north past the rebels/faery and across the bridge to the next section, once there you'll face a brummbear with possibly a few hawks - you can run past them heading north down the broken bridge that attaches to a hillside that has a path descending, at the bottom are more enemies and a narrow pass leading west - take it - and you should be in a isolated area with a crystal at the end 'in this area the "ultimate shield" or Patriot will appear' beat them and smash the crystal it contains the fourth page.
[Spoiler] Page Five, in the area just before you face Warcadia's Folklore (So 'Fort Avalon' the area that is through the door past the third teleport) will be numerous enemies Hawks, Bullseyes and Ga-dearg defeat them all and you should find in the second part of this area (where the crystals are floating) that one of them (once all the areas enmemies are beat) will contain the fifth page.
Pages 1-4-5 information on Keats Picture Book courtesy of CatalystGamers