HTML 4.01 Specification
W3C Recommendation 24 December 1999
This version:
http://www.w3.org/TR/1999/REC-html401-19991224
Latest version of HTML 4.01:
http://www.w3.org/TR/html401
Latest version of HTML 4:
http://www.w3.org/TR/html4
Latest version of HTML:
http://www.w3.org/TR/html
Previous version of HTML 4.01:
http://www.w3.org/TR/1999/PR-html40-19990824
Previous HTML 4 Recommendation:
http://www.w3.org/TR/1998/REC-html40-19980424