Research into the Benefits of Fake Smiles and the page it leads to and the pages it leads to. It cites these sources

      Can Smiling Make You Happy? Research and Teaching Showcase. Department of Psychology, University of Alberta. April 1998.

      Goleman, Daniel. A Feel-Good Theory: A Smile Affects Mood. The New York Times. July 18, 1989.;=&pagewanted;=all

      Lienhard, John H. No. 883: Smiles That Make You Happy. The Engines of Our Ingenuity. University of Houston College of Engineering.

    I am reluctant to cite websites as many have short lives but you will find still more if you type such words as smile research in a search engine.