Originally Posted by johnny o

"believe" is the keyword here.

if there are images shot by 20 different photographers (hypothetically) then you'd need 20 releases of copyright from each photographer. that certainly will be a feat.

also, if you think you're off the hook because the photographer may be dead (images from the 60's could very well mean so), copyright is valid in the U.S. up until 70 years after the copyright holder has died.