Some documents listed in the HEAR bibliography are in the HEAR document collection. If you have made a sincere effort to find the document elsewhere (e.g., via your local library or via interlibrary) and cannot find a particular document but need a particular piece of information, you may request specific information from HEAR. Subject to time availability, HEAR staff might be able to send you a photocopy of a relevant portion of a specific document within the constraints of fair use with respect to copyright.