Bass Heads

Hi all. I'm looking for a schematic of a transistor electric bass amp head. I found for now the schematich of the little mark lll by marbass but there is no legend on the web that clearly describes the circuit. Can you tell me where I can find a well-described schematic? I would also like to ask you if you could advise me about magazines or books on electric bass heads. Thanks in advance.

 

because I would like to develop a thesis on the various categories of electric bass amplifiers.