Источники

Helliwell, Layard, J. 2019. World Happiness Report 2019. New York: Sustainable Development Solutions Network.

Shepard, Roger N., and Jacqueline Metzler. 1971. “Mental Rotation of Three-Dimensional Objects.” Science 171 (3972): 701–3. https://doi.org/10.1126/science.171.3972.701.