Changes

*[https://positivepsychology.com/gratitude-appreciation/ What is Gratitude and Why Is It So Important?] by Tiffany Sauber Millacci, Ph.D., Positive Psychology website

*[https://ggsc.berkeley.edu/images/uploads/GGSC-JTF_White_Paper-Gratitude-FINAL.pdf The Science of Gratitude] by Greater Good Science Center

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