( ( these nucleons ) ( ( are ( formed ( of ( ( ( even smaller ) particles ) ( called ( elementary ( ( particles or ) quarks ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT these) (NNS nucleons)) (VP (VBP are) (VP (VBN formed) (PP (IN of) (NP (NP (ADJP (RB even) (JJR smaller)) (NNS particles)) (VP (VBN called) (NP (JJ elementary) (NNS particles) (CC or) (NNS quarks))))))) (. .)))
these nucleons are formed of even smaller particles called elementary particles or quarks.
(ROOT (S (NP (NP (DT The) (JJ subatomic) (NNS particles)) (PP (IN of) (NP (DT the) (NN nucleus)))) (VP (VBP are) (VP (VBN called) (NP (NNS nucleons)))) (. .)))