Helm, Lothar2006-09-192006-09-19200610.1016/j.pnmrs.2006.03.003https://infoscience.epfl.ch/handle/20.500.14299/234068WOS:0002408105000039335NMRparamagneticrelaxationcontrast agentsRelaxivity in paramagnetic systems: Theory and mechanismstext::journal::journal article::review article