\input zb-basic
\input zb-ioport
\iteman{io-port 50274963}
\itemau{Liu, Xingyuan; Liu, Yuji}
\itemti{On positive periodic solutions of functional difference equations with forcing term and applications}
\itemso{Computers & Mathematics with Applications 56, No. 9, 2247-2255 (2008).}
\itemcc{}
\itemut{}
\itemli{doi:10.1016/j.camwa.2007.12.017}
\end