Resources available for finding archives and navigating their collections vary widely by international context and archive type.
This guide suggests various print and digital research tools and guides to official archives and personal papers. It includes guides that contain a significant level of detail about collections, and as a rule, does not list directories of archives (for which there are many) that contain only addresses and brief summaries.
Its goal it to allow researchers working in international archives in various fields a place to begin.
Archival collection descriptions held by libraries, museums, historical societies, and academic archives. Has over one million descriptions including MARC catalog records from WorldCat and finding aids harvested from the web (EAD/XML, PDF, HTML).
Google "finding aid" and keywords to locate archives.
Rare books go through a more time-intensive cataloging process ("original cataloging"). During the process, catalogers record important details about the book (ie., inscriptions, handwritten annotations, former owners, limited editions, other unique properties). These notes are typically in a special section of the catalog record, called "notes applicable only the the local library."
To find rare books in the Rose Library use discoverE. Search for the title that you are interested in followed by MARBL.
List of 'special' libraries organized by country. See Western United States and Canada. Eastern United States and Canada: States and Provinces, A-M. Eastern United States and Canada: States and Provinces, N-Z.