NIST has published over 250 Special Publications, FIPS standards and guidelines on IT security, all available for free download from the NIST Computer Security Resource Center. There are so many that newcomers tend to be overwhelmed by the choice. NIST's response is to publish yet another document - a guide to their publications that categorises them by 'family', by topic cluster and by [US] legal requirement.
The choice of a PDF document for the guide was presumably a no-brainer for NIST and, I guess, will suit people who like reading printed documents. I hate to criticise NIST but the guide doesn't even have URLs for the listed documents. New draft and final standards are published every month but the guide will only be updated twice a year.
The Google search box on the CSRC home page has the advantage of easier, more flexible and more up-to-date searching. I think I'll stick to that, thanks.