A short proof is given that the graphs with proper interval representations are the same as the graphs with unit interval representations. © 1999 Elsevier Science B.V. All rights reserved.
Bogart, K. P., & West, D. B. (1999). A short proof that “proper = unit.” Discrete Mathematics, 201(1–3), 21–23. https://doi.org/10.1016/S0012-365X(98)00310-0