Collins, B. L. (1982). The development and evaluation of effective symbol signs. U.S. Dept. of Commerce, National Bureau of Standards : For sale by the Supt. of Docs., U.S. G.P.O.
Lua i Stíl Chicago (17ú heag.)Collins, Belinda Lowenhaupt. The Development and Evaluation of Effective Symbol Signs. Washington, D.C.: U.S. Dept. of Commerce, National Bureau of Standards : For sale by the Supt. of Docs., U.S. G.P.O, 1982.
Lua MLA (8ú heag.)Collins, Belinda Lowenhaupt. The Development and Evaluation of Effective Symbol Signs. U.S. Dept. of Commerce, National Bureau of Standards : For sale by the Supt. of Docs., U.S. G.P.O, 1982.
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