Per 
Library of Chains: SCP-XXXX
Object Class: Keter with possible reclassification as Thaumiel
Special Containment Procedures: The chains in use at the site must be made from electrum with an exact composition of fifty-five percent silver, forty percent gold and five percent platinum without exception. An inspection of the chains must be conducted every week to ensure the chains are in top condition. Any chains with evidence of corrosion are to be reported for immediate replacement.
No books are to be brought into or out of the library under any circumstances. Any personnel entering the library are to attach their cord to the provided hook and keep the spool on their person at all times. Upon entering and exiting the Library personnel are required to ring the provided bell once.
Description: The entity is a library discovered at site █████ in ████ by a research team under Dr.███████. The observable dimensions of the library do not exceed one hundred metres by one hundred metres, with a minimum of four observable floors designed similarly to wraparound balconies. The library dates back to a minimum of ████ with the intention of storing unusual artifacts, specifically those that take the form of books. Recent analysis suggests it may have been the work of a precursor to the current SCP Foundation.
The nature of the artifacts stored here seems to books, usually those that are fiction, that have been unknowingly turned into Objects Of Power. Any of these books, if left unchecked, will start to alter the laws of reality around them to align with the law of the book's content. The library itself seems to be a natural formation, combined with specific additions that drastically slows the rate at which the conversion takes place. The only method that prevents any destructive conversion and clashes between the different laws in the various books is the chains. The specific composition of the chains in conjunction with the natural formation and additions, prevents any of the more overt potential destructive effects, but cannot completely negate this effect.
Books appear with relative frequency by themselves in the library, some that have not been published at the time or contain details of alternative histories. The library also seems to have had the space it occupies folded in on itself, creating a series of dimensional layers to the library. To date ████ individuals have vanished into the library and are most likely deceased, due to starvation, thirst or old age.
The library contains the potential to be useful in securing other items of a book form, however the library seems to alter the properties of any books that enter, assimilating them as part of the library. One of the possible issues that may occur is that allowing the library to assimilate other books that are currently under SCP care may cause the current procedures to cease effectiveness, causing the conversion to become uncontrollable with undesirable effects including, but not limited to: allowing entities from the books to escape and roam free, opening a permanent portal that other entities may take advantage of to invade or plunder Earth or allowing dark matter to form and cause mass destruction. Worse scenarios could reach the level of trapping Earth between dimensions, creation of a black hole, total conversion of the planet into that found in one of the books within.
An unknown possibility is using the library and the books contained within to find alternative access points in some the inter-dimensional spaces related to other entities under SCP jurisdiction, however until the current methods of suppression can be fully understood, no actions shall be taken to research this possibility.
The small bell is provided as method of pacifying the be entities that occupy and guard the place, temporarily termed "Librarians" henceforth. They usually are hidden away and don't cause issues for the researchers, as long as the containment procedures are followed. Any attempts to take a book from the library, tamper with the chains (See report ████) or damage the books are met with extreme aggression, causing them to show themselves and hunt the perpetrator down until the perpetrator is killed.
The Librarians can take different forms, seemingly dependent on age and the amount of infractions dealt with prior, most observations and research concluding the the amount of infractions dealt with has a more pronounced effect. Most are about ninety centimetre tall humanoids, covered in a silver mist that prevents any further details from being observed. The librarians that are vastly older or deal with more infractions vary greatly in terms of size and strength. The largest current specimen to be observed stands at five metres tall and was capable of limited manipulation of the Library's structure and overlapping dimensions to corner and kill the perpetrator.
