If you are not citing the original source – which should generally be used (!) – but instead must cite a secondary source because the original is no longer accessible, both sources must be listed. The original work is cited first, followed by the reference “cited in” for the source from which the original reference was obtained. Here is an example in APA style:

Penrose states: “it is never resources themselves that are the 'inputs' to the production process, but only services that the resources can render” (Penrose, 1959, pp. 24–25, cited in Vargo & Lusch, 2004, p. 326).