http://www.multi.fi/~samppo/hifi.htm
http://www.quarter-a.netfirms.com/
http://www.zwillingssterne.de/pm35.html
http://www.thevintageknob.org/MARANTZ/MARANTZ-main.html (http://www.thevintageknob.org/MARANTZ/MARANTZ-main.html)
http://www.radiomuseum.org/dsp_search.cfm