(S (S (PP (VBG According) (PP (TO to) (BASENP (NNS researchers)))) (COMMA ,) (S (NP (BASENP (DT the) (NN shoe)) (PRN (COMMA ,) (VP (VBN made) (PP (IN of) (BASENP (NN cow-hide)))) (COMMA ,))) (VP (VP (VBZ consists) (PP (IN of) (BASENP (QP (RB only) (NN one)) (NN leather) (NN piece)))) (CC and) (VP (VBD was) (VP (ADVP (RB probably)) (VP (VBN customised) (PP (TO to) (NP (BASENP (DT the) (NN wearer) (POS 's)) (NN foot))))))))) (PERIOD .))