In the general case of an old newspaper which may not be scanned and online, a URI (i.e., an indentifier) is called for; in the case of an old newspaper which has been scanned, a URL is called for.
The distinction is that an identifier identifies a resource; a locator states where it is located.
'My grand-father's diary, 4 July 1930' is a resource identifier (but not a URI); urn:isbn:0-486-27557-4 is a URI, but not a URL; https://news.ycombinator.com/ is a URL.
The distinction is that an identifier identifies a resource; a locator states where it is located.
'My grand-father's diary, 4 July 1930' is a resource identifier (but not a URI); urn:isbn:0-486-27557-4 is a URI, but not a URL; https://news.ycombinator.com/ is a URL.