Richards, J. A. (1983). Analysis of periodically time-varying systems. Springer-Verlag.
Lua i Stíl Chicago (17ú heag.)Richards, J. A. Analysis of Periodically Time-varying Systems. Berlin, New York: Springer-Verlag, 1983.
Lua MLA (9ú heag.)Richards, J. A. Analysis of Periodically Time-varying Systems. Springer-Verlag, 1983.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.