遡る[sakanoboru] to go back
遡及[sakkyuu] tracing back
遡源[sakugen] returning to the origin
遡及的[sokyuuteki] retroactive
遡上[sojou] going upstream

遡航[sokou] going upstream
遡求[sokyuu] redemption
遡河魚[sokagyo] anadromous fish (fish that migrates upstream, e.g. salmon)
遡及書誌[sokyuushoshi] retrospective bibliography
遡求権[sokyuuken] right of recourse