New Fundamental dHvA Frequency in Canonical Low-Dimensional Fermi   Liquids
  We show that a new fundamental period $P_{f}$ of dHvA oscillations, which appears along with other ``forbidden'' combination frequencies in a multi-band canonical Fermi-liquid, is very robust with respect to a finite smearing of Landau levels and a background of non-quantized states. We analyse the possibility of measuring small Fermi surface pockets with the use of the ``forbidden'' frequencies. 
A.S. Alexandrov(1) and A.M. Bratkovsky (2) ((1) Loughborough, UK; (2)   Hewlett-Packard Labs, USA)