Miaghstir: No weblinked resources that I know of. Most of the information I've found in the various Myst games and books (the Books of Atrus, Ti'Ana, and D'Ni; as the Myst Reader) - and, yes, websites - have blurred together so I no longer know where I picked up each bit of information. Gehn is steadfast in his vision that he is the creator - and thus god - of the worlds he writes books for, while Atrus (the younger, not Atrus/Aitrus, father of Gehn - don't remember his stance, or even if it is revealed) and Katran/Catherine are of the opinion that there are an infinite number of worlds, and that by describing them in a "master book" (I forget what they're actually called) you merely create links to them, and then the smaller carryable (usual) linking books link to a passage within the master book and thus to a place in that world.
Also: In Myst, Atrus destroys the prison books in which his sons are trapped, but in Myst 4, they are back. (But then, some things that are said to be impossible, have been proven to be, in fact, fully possible - like linking to another place in the same world, and taking the linking book with you (both being discoveries/inventions by Yeesha, and being shown to the players in Uru.)
M15aNtHrOpE: I think it is entirely possible for the Books that Atrus destroyed to have been the Linking Books to those worlds. If I'm not mistaken, the brothers weren't trapped in the Prison worlds, but trapped between Ages in MYST 1(hence the few pages torn out and thus could not escape), but then it would be assumed that the brothers would have been killed in the canon ending.
According to the D'ni Restoration Council, there can be two Books for each Age: One is the Descriptive Book (your "master book"), which may in itself contain the Link, and also the Linking Book, for Ages for which a Link is not provided in the Descriptive Book.
According to what I have read (again, sorry, no link, only memory), the description book (thank you for the correct term) can be used to link as well, but since there is only one of it, and it's much too large and heavy to bring around with you, the smaller linking books are used instead.