-tree bbbee be-er bebel beber beebe beele beete beeut belee belet bellb belle belue belur belut berbe berel beret berle berre berru berte betee betel beter betle betre bett- bette betul beuer beule beure beute bleer bleet blere blete bleue bluer bluet blurb blure blurr blurt brebu breel breer breet brell brere brett breu- brrrr bruer bruet brule brull brute btr-t bubbe buber buble buell bulb- bull- bulle bulul bulut burel buret burle burru burte burtt burut buter butle butte butut ebber ebbet ebble ebell eberl ebert eblul ebull ebure eeeee eeler eleet elele eleut ellel eller ellet ellul elulu eluru elute erbbe erber erere errtu erte ertel erter etete etree ettel etter ettle eturu euell euler eurel eurre lebel leber lebet leell leere leert leleu lelle lerer letbe letre lette letur lubbe luber luble lubur lulle lulte lulul lurer lurue lute- luter lutte rebbe rebel reber rebet rebut reere relee relet relte relue rere- reree reret retee retel reter rette reuel reuer reuet reule reute rubee rubel ruber ruble ruele ruell ruere ruete ruler ruter rutle rutte rutul ruule ruutu tbtbt tbutt teber tebet teele teell tele- teler teleu tell- telle teret tereu terre tert- tetel teter tetle tetr- tette tlell tlett tllbr treer treet trele trere trete trett treut trubu truel truer trule trull trute ttttt tuber tubul tuell tuelt tulet tulle turbe turbt turel turet turle turre turtu turul turut tutee tutel tutle tutte tuuru ubble uber- ullet ullur ultre ululu uluru urelu urtel urter urtlu urubu urutu uter- utter uttur utube uturu uuuuu