  Here, we present the results of theoretical analysis of the de Haas-van
Alphen oscillations in quasi-two-dimensional normal metals. We had been
studying effects of the Fermi surface (FS) shape on these oscillations. It was
shown that the effects could be revealed and well pronounced when the FS
curvature becomes zero at cross-sections with extremal cross-sectional areas.
In this case both shape and amplitude of the oscillations could be
significantly changed. Also, we analyze the effect of the FS local geometry on
the angular dependencies of the oscillation amplitudes when the magnetic field
is tilted away from the FS symmetry axis by the angle $\theta.$ We show that a
peak appears at $\theta \approx 0$ whose height could be of the same order as
the maximum at the Yamaji angle. This peak emerges when the FS includes zero
curvature cross-sections of extremal areas. Such maximum was observed in
experiments on the $\alpha-(BETS)_4TIHg(SeCN)_4.$ The obtained results could be
applied to organic metals and other quasi-two-dimensional compounds.
