If you are looking for physical handbooks, these authors are the "gold standard" for Nikon-specific guides:

: Known for incredibly dense, technical "Complete Guides" to specific Nikon bodies.

: His "Mastering" series provides a great balance of tutorial and reference.

: One of Nikon's greatest strengths is the ability to use vintage F-mount lenses on modern DSLRs or Z-series mirrorless bodies via the FTZ Adapter.