. "inferior epigastric vein tributary_of external iliac vein" . . "drains to" . . "http://en.wikipedia.org/wiki/Tributary" . . "tributary of"@en . "http://www.medindia.net/glossary/venous_tributary.htm" . . . . "http://en.wikipedia.org/wiki/Tributary"^^ . . "This relation can be used for geographic features (e.g. rivers) as well as anatomical structures (veins, arteries)"^^ . . . "Chris Mungall" . . . "x tributary_of y if and only if x a channel for the flow of a substance into y, where y is larger than x. If x and y are hydrographic features, then y is the main stem of a river, or a lake or bay, but not the sea or ocean. If x and y are anatomical, then y is a vein." . . "drains into" . . "tributary channel of" . "Deschutes River tributary_of Columbia River" .