Corduneanu, Silvia-Otilia. “ A Density Property of the \(C^\ast\)-Algebra Pap(R) and Its Applications”. Rev. Anal. Numér. Théor. Approx., vol. 27, no. 2, Aug. 1998, pp. 219-25, https://ictp.acad.ro/jnaat/journal/article/view/1998-vol27-no2-art3.