They do not know it themselves.'  
( They ( ( ( ( do not ) ( know ( it themselves ) ) ) . ) ' ) )
(ROOT (S (NP (PRP They)) (VP (VBP do) (RB not) (VP (VB know) (S (NP (PRP it)) (NP (PRP themselves))))) (. .) ('' ')))
They have no knowledge of it themselves.
( They ( ( have ( ( no knowledge ) ( of ( it themselves ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP have) (NP (NP (DT no) (NN knowledge)) (PP (IN of) (NP (NP (PRP it)) (ADVP (PRP themselves)))))) (. .)))