Light passing through a standard single prism is refracted twice—once upon entering the prism and once upon exiting—bending in the same general direction at both interfaces, making this a matter of basic geometric optics that requires no citation.
Light passing through a prism is refracted as it enters and exits, but not bent in the same direction twice in a continuous path.
The claim describes basic optics regarding how light behaves when passing through a prism (refracting at the entrance and exit interfaces). None of the retrieved papers specifically evaluate the exact phrase 'bent in the same direction twice,' but standard physical optics establish the principles of refraction. The claim is treated as common knowledge or a straightforward description of refraction at multiple boundaries.