where did these popular aeroplanes - allison model 250 and pratt & whitney r-2800 double wasp originate ?
SELECT DISTINCT var_uri where brack_open dbr_Allison_Model_250 dbp_nationalOrigin var_uri sep_dot dbr_Pratt_&_Whitney_R-2800_Double_Wasp dbp_nationalOrigin var_uri brack_close