We have detected and analyzed narrow, high contrast coherent population trapping (CPT) resonances, which appear in transmission of the probe monochromatic light beam under action of the counter propagating two frequency laser radiation, on example of the nonclosed three level A-system formed by spectral components of the Doppler broadened D 2 line of cesium atoms. Given resonances may be used in atomic frequency standards, sensitive magnetometers and in ultrahigh resolution laser spectroscopy of atoms and molecules.