surse:http/www.atitudinea.ro/articole/diverse/cum+sa+deosebim+zambetul+fals+de+cel+sincer

http://www.bbc.co.uk/science/humanbody/mind/surveys/smiles/

http://longevity.about.com/od/lifelongbeauty/tp/smiling.htm

http://www.romania-actualitati.ro/zambetul_prelungeste_viata-11872