So, I updated from 1.2.0i to 1.2.1a plus Enchiridion 1.0a ( MC 1.6.4, customized Monster pack ), I was reading Mariculture book "Basic Materials and processing" and on page 3 got crash ( tested also Fishing book and on opening same thing happened ):
edit: just click on arrow prevoius/next page.

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.substring(Unknown Source)
at enchiridion.api.StackHelper.getItemByText(StackHelper.java:39)
at enchiridion.api.StackHelper.getStackFromArray(StackHelper.java:26)
at enchiridion.api.StackHelper.getStackFromString(StackHelper.java:8)
at enchiridion.api.DisplayRegistry.getIcon(DisplayRegistry.java:58)
at enchiridion.api.pages.PageCrafting.parse(PageCrafting.java:33)
at enchiridion.api.GuiGuide.draw(GuiGuide.java:126)
at enchiridion.api.GuiGuide.drawPage(GuiGuide.java:137)
at enchiridion.api.GuiGuide.drawLeftPage(GuiGuide.java:157)
at enchiridion.api.GuiGuide.func_73863_a(GuiGuide.java:205)
at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1036)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:946)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

I can confirm this, tho I only get the same crash when I open the Factory and the Fishing Book

I've checked all ids and none of the are conflicting. The 2 mods that mariculture items are in between are both 200+ ids apart. I'll post my Log file maybe it will help somewhat. https://gist.githubusercontent.com/atsivertes/d794592d966a36d3758c/raw/3c626f75b830b08e5d0d6903008ce35cd22ffdf8/sss

Already fixed by Joshi :D.
http://www.minecraftforum.net/topic/2049315-164172mariculture-121a-172-beta-1-updated-24032013/page__st__660#entry29964307

As he said ^ fixed in Enchiridion 1.0b

Please check your item ids aren't conflicting. It's the only way I can think of, that this could happen. I'll make it not crash, but I doubt it will solve the problem.