X-Factor updating and total factor productivity growth: the case of peruvian telecommunications, 1996–2003.Published in:Journal of Regulatory Economics, 2006, v. 30, n. 3, p. 316, doi. 10.1007/s11149-006-9000-1By:Bernstein, Jeffrey I.;Hernandez, Juan;Rodriguez, Jose Maria;Ros, Agustin J.Publication type:Article