b-tree bbbbbb beebee beefer beeker beeter befree befret bekker berbee berber bereet bereft bereke berere berker berkut berrer berret bertre berube betere betete betrue bettee better betutu beurre breefe breere brekke brette breuer brubru brufut bruker bruket bruree bubber bububu buffer buffet bukett bukkur bukuru burbet burbur burfee burket burkut burree burrer burret buruku burutu butere butter ebbert eburru eebree effere effete effutu efreet efter- erbree erfurt erketu errett ettutu eutere fekete ferber ferfer ferrer ferret ferrur fertee fertek ferter fetter feture feuter frefre frette freure fterer fterre fuerte furber furfur furrer furrfu futret futter future k-tree kebber keefer keeffe keeker kekkut kerber kereft kereru kerker kerkuk kertee ketter ketuke keuruu krefft kreker kretek kubeer kukere kurree kururu kutke kutter r-tree rebuff rebuke rebute reefer reeffe reeker refeet refeff refert refete refret refter refurb refute rekrut reteer reteet retere retree retret retter rettur retube returf returu reubke reuere reuter reutte rubbee rubber rubutu rufete ruffer ruffet rufter rukutu rurkee rurutu ruttee rutter rutube t-tree t-tube teebee teetee teeter tekfur tekrur terbuf terete terrer terret terter tertre tetete tetter trebek trebur treete trefet trefte treker tretee trette tretuk truett trufte truker tubber tuffet tufter tuktuk turbet turfer turker turret turtuk turtur tururu tuteur tutter tuttut u-tube ufreet ureter urette uruffe uteute utukku utukur