SIMBAD references

In this paper the Fourier decomposition was applied to photoelectric and CCD measurements of faint Cepheids for which the light curve was supplied for the first time with a sufficient accuracy. The Fourier decomposition is confirmed to be a pulsation mode discriminator and this property is discussed by considering also the case of the double-mode Cepheid TU Cas. The analysis allowed us to detect three new first overtone pulsators and to better define the behaviour of the Hertzsprung progression for classical Cepheids with P<3 d. Some uncertainties are left only for Cepheids located exactly on the discontinuity at P ≃3 d and for Cepheids with an apparently perfect sinusoidal light curve. At the present time, the Fourier decomposition cannot be used to discriminate safely between Pop. I and Pop. II stars. However, more numerous and precise measurements should allow us to clarify also these open questions.