Im not suggesting a definition of terms or that a formal distinction between electric and electronic even exists  But I dont think we need references to accept that many people have a narrow conception of electronic  Google books certainly believes that electric amplifier is a term  You might also want to consider electric guitar amplifier  hits against electronic guitar amplifier  hits although that term should perhaps be taken as electricguitar amplifier  In any case it really doesnt matter since the proposed article title is simply Amplifier