Regarding Topps Proof & Goofs I found the following set of articles interesting:
http://www.sportscollectorsdigest.co...roofs-part-one
Regarding Topps Proofs Part II:
http://www.sportscollectorsdigest.co...roofs-part-two
Regarding Topps Proofs Part III:
http://www.sportscollectorsdigest.co...ermannproofiii
Interesting stuff.
Zach Wheat