\input zb-basic \input zb-ioport \iteman{io-port 03791922} \itemau{Bergman, Bo; Klefsjoe, Bengt} \itemti{A graphical method applicable to age-replacement problems.} \itemso{IEEE Trans. Reliab. 31, 478-481 (1982).} \itemcc{} \itemut{graphical method; maintenance; availability; total time on test concept; TTT-transform; age-replacement} \itemli{doi:10.1109/TR.1982.5221439} \end