Changes in Structural and Electronic Properties of the Zeolite Framework Induced by Extraframework Al and La in H-USY and La(<i>x</i>)NaY: A<sup>29</sup>Si and<sup>27</sup>Al MAS NMR and<sup>27</sup>Al MQ MAS NMR StudyJeroen A. van Bokhoven, Arno P. M. Kentgens, A. L. Roest et al.|The Journal of Physical Chemistry B|2000Cited by 198