See below a list of various articles and reference materials which may help reading smith signatures.

Miscellaneous

New Member's Guide to Nihonto Club

About Swordsmith Index

List of Japanese Provinces

Goban Kaji

Archaic pronunciation of swordsmith names. List of alternative readings

Reverse Kanji Lookup Table

List of articles in Albert Yamanaka's Nihonto Newsletter

How to read Nihonto Meikan

Attribution of zaimei Ichimonji swords

Pete McCollum's Kanji tables

Kanji Identification List - Sorted By Stroke Count

Kanji Identification List - Sorted Alphabetically