which leader of grand duchy of oldenburg married to princess adelheid of anhalt-bernburg-schaumburg-hoym ?
SELECT DISTINCT var_uri where brack_open dbr_Grand_Duchy_of_Oldenburg dbp_leader var_uri sep_dot dbr_Princess_Adelheid_of_Anhalt-Bernburg-Schaumburg-Hoym dbo_spouse var_uri brack_close