Jugtail - An open source search engine system for the Gopher protocol. Jugtail, formerly known as Jughead, searches one server at a time whereas Veronica doesn't have this limitation.
PyGopherd - An open source multi-protocol gopher server written in Python. Also works as an HTTP and WAP server.
PyGS - Open source Gopher server written in Python. No longer being developed.
RFC 1436 - The Internet Gopher Protocol (a Distributed Document Search and Retrieval Protocol). F. Anklesaria, M. McCahill, P. Lindner, D. Johnson, D. Torrey, B. Albert. March 1993.
Spencer Hunter's Homepage - Example of a Gopher emulation in HTML, online since 1995. Under the "About this gopher and myself" directory is the author's own Gopher manifesto, "Why gopher is superior to the Web."
Veronica FAQ - Common questions and answers about Veronica, a title search and retrieval system for use with the Internet gopher.
TidBITS: Down the Gopher Hole - A brief presentation of the protocol, both its history and its current status, by an experienced Gopher system administrator.