Citation: Rakic, S.; Kahlenberg, V.; Schmidt, B.C. (2003). High pressure mixed alkali disilicates in the system Na2-x Kx Si2 O5: hydrothermal synthesis and crystal structures of Na K Si2 O5 - II and Na0.67 K1.33 Si2 O5. Zeitschrift fuer Kristallographie (149,1979-), 218, pp. 413-420.