પ્રત્યાયન : સંજ્ઞાઓ અને સંકેતો

https://www.sciencealert.com/watch-why-do-we-use-symbols

https://study.com/academy/lesson/what-is-visual-communication-definition-history-theory-examples.html

https://study.com/academy/lesson/facial-expressions-in-nonverbal-communication-importance-lesson-quiz.html

http://humanorigins.si.edu/human-characteristics/language-symbols

https://beachsafe.org.au/surf-safety/flags-and-signs

https://www.prweb.com/releases/2018/02/prweb15222949.htm