ASYMMETRIC SHUBNIKOV-DE HAAS OSCILLATIONS AND HALL PLATEAUS OF HETEROJUNCTIONS IN THE QUANTUM HALL REGIME R.R. GERHARDTS, R.J. HAUG and K. PLOOG J. Phys. Colloques, 48 C5 (1987) C5-227-C5-230 DOI: 10.1051/jphyscol:1987547