汚染源[osengen] source of pollution
音源[ongen] sound source
禍源[kagen] source of misfortune
供給源[kyoukyuugen] source of supply
経営資源[keieishigen] management resource

源氏物語[genjimonogatari] the Tale of the Genji
源泉[gensen] source
源流[genryuu] current-limiting
語源[gogen] word root

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