What makes scientific article a classical?
First, and more commonly used is number of citations.
Second definition of a classic scientific article is inherent to article itself. These articles are so completely innovatives and disruptive that new protocols have been implemented and new and results have been achieved.
I would appreciate so much if you could answer a fast online questionaire about historical articles:
https://docs.google.com/forms/d/e/1FAIpQLSfPg8Lkmuug5CsJUvpG6lDNMN8aRpotVYn-eDnbYLmeIwpUmQ/viewform?usp=sf_link
And please send to your pairs, globally if possible.
Best regards