Item NBT tag (I think)

I want to make a GUI where we can get an enchanted book but I have a problem, I don't know how I can make appear an enchanted book which is margeable with others items with an anvil in my GUI (I have try to enchant it with the enchant block but it just cannot be merged with items in anvil) I have searched a lot of time and I havn't find anyway about this topic but I think I have to use the NBT tag block but I don't really know how to use it, so help me please, thanks...