@techreport{oai:tsukuba.repo.nii.ac.jp:00022860,
 author = {Sumita, Ushio and Yoshii, Jun},
 month = {Feb},
 title = {On Relationship between Ergodic Sojourn Time and Ergodic Residual Exit Time for Semi-Markov Processes},
 year = {2008}
}