where to find the year and conference of a scientific article?
Background: Many researchers put their articles for download on their personal web pages. As most publishers insist on not allowing the researcher to put the "official" version there, but rather only the self-made PDF, this leads to articles often not having the journal/conference information on the first page (as this would require changing the article a bit, which is a bit of work to be done). Also, self-archived versions often appear before the conference, so that page numbers can only be missing, and might not be updated later.

Actual Answer: For CS, a good strategy is to just type "DBLP " into your favorite search engine. Many papers nowadays are listed on the DBLP page, which also allows you to just download the bibliographic information.

If a paper is not listed on DBLP, just searching for the paper title often yields the publisher's page of the article, which should have the information available.

If searching for the title does not yield any results, then the paper could be a limited circulation pre-print, which is stricly speaking not citeble. However, in such (hopefully few) cases, it makes sense to ask the person who gave you the article for bibliographic information.