As an aside: Is it not required to put a date of publication inside scientific papers? I've always thought that documentation was paramount for papers such as t

As an aside: Is it not required to put a date of publication inside scientific papers? I've always thought that documentation was paramount for papers such as these, and as such the date would be one of the primary pieces of information present, but I've come across many papers (including this one) for which I had to find publication information on third party websites (for this particular paper: Researchgate)