According to my '77 Ram edition, #6 was copyrighted in 1961.
Revised printings in '73. '74 and '77. Ram Publishing Co. was in
Dallas and was used by Charles Garrett, Roy Lagal and KVM.
I don't know who printed the earlier versions so I can't say what was
left out. I wonder how many young guys like I was then were turned
on to real treasure seeking by the master, Karl von Mueller?
THM #7 was copyrighted '71. I have the '72 RAM edition. Roy
Lagal's Detector Owner's Field Manual came in '76 by RAM. I never
hear much about Roy anymore. He was a true Pro and could explain
how detectors work as good as anyone.
KVM (Deek Gladson's) "Sudden Wealth" came out in '72, I have the
'74 RAM edition. Charles Garrett's "Successful Coin Hunting" came out
in '74. I bought one and Charles gave me a signed copy in '77 for
bringing him a folding Army shovel.
Ahh, nostalgia lastleg