The tools you need for successful implementation
The SMB Implementation Book --This book provides low-cost, practical suggestions for each of the NIST SP 800-171 requirements.
Revision 2 of the official NIST SP 800-171 standard --The thumbnail links to the NIST website to download the official standard.
Government's CUI FAQ -- This document contains answers to questions that have been asked about the implementation of NIST SP 800-171.
NIST SP 800-53 -- By using the table in the back of 800-171, you can look up specific areas in this standard for better understanding of their intent.