Thank you Ferito and Jirk5, I will start my research in oldradio.cz. However, as Ferito adviced, M37 and M371 are completely different, having M37 only 4 tubes (AZ1, AL4, TAF7 e AF3), whilst M371 has 5 tubes, they have only the AZ1 in common. In any case, if someone has a scheme with the same 4 tube...

Hi everybody,
I am an Italian collector, I have a 4 valves Markofon M37, but no scheme.
Can somebody help?
Thank you in advance!