Mustăţa, C. “On the Extension of Semi-Lipschitz Functions on Asymmetric Normed Spaces”. Rev. Anal. Numér. Théor. Approx., vol. 34, no. 2, Aug. 2005, pp. 139-50, https://ictp.acad.ro/jnaat/journal/article/view/2005-vol34-no2-art3.