Adult Sex Differences in the Concept of Horizontality as Related to Mechanical Ability,Act Scores and State Anxiety

Rebelsky F. Adult perception of the horizontal. Perceptual and Motor Skills, 1964, 19, 371–374.

Smedslund J. The effect of observation on children's representation of the spatial orientation of a water surface. Journal of Genetic Psychology, 1963, 102, 195–201.