Last month at a garage sale Â* I came across a large stack of Popular
Electronics and other electronic magazines from the 50¹s 60¹s and 70¹s

Under US copyright law, Popular Electronics et al own the rights to all of
the material in those magazines. You do not have any legal right to sell
copies
of that material! You can quickly find yourself in trouble if you try
this - you've
made it so high profile posting here that I'm sure you'll get a 'cease and
desist'
order from PE legal eagles (does not matter if the mag is still published -
under
US copyright law the comapany can be fully out of business but still own the
copyright and can still sue you).

Good luck.