Mantzios, Michail, i in. „Adult Colouring: the Effect of App-Based Vs. Pen-and-Paper Colouring on Mindfulness and Anxiety”. Health Psychology Report, t. 7, nr 4, październik 2019, s. 286-95, https://czasopisma.bg.ug.edu.pl/index.php/HPR/article/view/7948.