Signage Standards for the Government of Canada:
Provides detailed guidelines for implementation of signage by Governmental bodies in Canada.
Federal Identity Program by Treasury Board of Canada Secretariat.

Literature on Research About Pictograms
A selection of papers, reports and books related to tests and design of graphic symbols as well as related subjects.

Creating Public Park Signages
From Project for Public Spaces (http://www.pps.org):
Article on signages that provide effective information and direction for people to find their way around the park; encourages learning experiences; helps maintain the image of the park; and communicates park rules.

Graphical Symbols to Address Consumer Needs
by John Perry,
Project Leader ISO COPOLCO
An article on developing graphical symbols and signs with the consumer in mind.

Meanings of the word 'Sign', 'Symbol' , 'Pictogram' and 'Graphics'
From Websters online dictionary - gives many of its associations and connections.