However, despite exhaustive research, I am reluctantly forced to resort to the familiar lexical locution, `Source unknown.
( However ( , ( ( despite ( exhaustive research ) ) ( , ( I ( ( ( am reluctantly ) ( forced ( to ( ( ( ( resort ( to ( the ( ( familiar lexical ) locution ) ) ) ) , ) ` ) ( Source unknown ) ) ) ) ) . ) ) ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (PP (IN despite) (NP (JJ exhaustive) (NN research))) (, ,) (NP (PRP I)) (VP (VBP am) (ADVP (RB reluctantly)) (VP (VBN forced) (S (VP (TO to) (VP (VB resort) (PP (TO to) (NP (DT the) (ADJP (JJ familiar) (JJ lexical)) (NN locution))) (, ,) (`` `) (NP (NN Source) (NN unknown))))))) (. .)))
After some time, I have discovered the first source I am looking for.
( ( After ( some time ) ) ( , ( I ( ( have ( discovered ( ( the ( first source ) ) ( I ( am ( looking for ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN After) (NP (DT some) (NN time))) (, ,) (NP (PRP I)) (VP (VBP have) (VP (VBN discovered) (NP (NP (DT the) (JJ first) (NN source)) (SBAR (S (NP (PRP I)) (VP (VBP am) (VP (VBG looking) (PP (IN for))))))))) (. .)))