ELECTROOPTICAL BEHAVIOR OF CHOLESTERIC BLUE PHASES WITH NEGATIVE DIELECTRIC ANISOTROPY
G. HEPPKE, H.-S. Kitzerow, M. KRUMREY, MOLECULAR CRYSTALS AND LIQUID CRYSTALS 1 (1985) 117–122.

ELECTRIC-FIELD INDUCED VARIATION OF THE REFRACTIVE-INDEX IN CHOLESTERIC BLUE PHASES
G. HEPPKE, H.-S. Kitzerow, M. KRUMREY, MOLECULAR CRYSTALS AND LIQUID CRYSTALS 2 (1985) 59–65.