Zenith angle distributions of cosmic ray muons

A review of measurements of the muon energy spectra for different altitudes, height and directions performed with devices placed at various geomagnetic latitudes is presented. In addition experimental data for angular distributions from underground laboratories are included. The idea of the present report is to explore whether serious sercrepancies exist among the various values and to give as far as possible a coherent view of the present muon zenith angle distributions knowledge. The fit to all the experimental muon data is presented