The printed form is ownable. And it is likely that the original publisher of the material owns the copyright to that material. The duration of copyright is "Written... work 70 years after the author’s death" (from gov.uk). This is so important that all (historical) Tektronix material made publicly available, no matter how old, needs specific permission from Tektronix. Likewise with HP. Neither organisation has thus far refused, and a treasure trove of information, old some company confidential (such as coil and transformer winding details), has been emerging.
That the company or organisation that produced the manual or datasheet no longer exists still does not work. Because even then someone owns the rights. A receiver will have taken responsibility for the intellectual assets of the organisation, and may have passed those assets on to a third party.
I'm not sure how
https://www.americanradiohistory.com/ has managed this trick, because it has a complete downloadable set of Wireless World and Practical Wireless (along with hundreds of other radio magazines).
Craig