How do I cite this apparently unpublished paper?

Question

How do I cite the paper The fundamental distinction between brains and turing machines, by Andrew Friedman?

Answer 1

If you want to cite something you found online that does not seem to be published elsewhere (in a journal, as part of a collection/book/conference proceedings, ...) you can always fall back to @online.

From the PDF alone you already have the author, a title and you can infer the year. Naturally you have a URL and the access date, so you could have

@online{friedman,
  author  = {Friedman, Andrew},
  title   = {The Fundamental Distinction Between Brains and Turing Machines},
  year    = {2002},
  url     = {http://web.mit.edu/asf/www/PopularScience/Friedman_BrainsAndTuringMachines_2002.pdf},
  urldate = {2019-06-19},
}

---

According to Andrew Friedman's web page http://web.mit.edu/asf/www/popular_science.shtml and his CV https://asfriedman.physics.ucsd.edu/MITResume/AndrewFriedmanCV.pdf this article was published in the Berkeley Scientific Journal, Vol. 6, Issue 1, Spring 2002, p. 28-33. The cover image of the journal in question available at http://afriedman.org/AndysWebPage/BSJ/Spring2002Cover.html as well as the short summary of the contents of the Spring 2002 issue at https://bsj.berkeley.edu/read-the-bsj/past-issues/ seem to corroborate that story.

Unfortunately, older volumes of the BSJ are not digitally available in their entirety. See also https://bsj.berkeley.edu/read-the-bsj/past-issues/. Newer versions can be found at https://escholarship.org/uc/our_bsj.

One may feel a bit uneasy about citing a publication with data that one could not verify completely and that is not particularly helpful to the reader (the BSJ issue in question is not available online and I doubt that a lot of people have access to the journal through their libraries), but if that is not an issue for you, you could also cite this entry as an @article

@article{friedman,
  author  = {Friedman, Andrew},
  title   = {The Fundamental Distinction Between Brains and Turing Machines},
  year    = {2002},
  journal = {Berkeley Scientific Journal},
  volume  = {6},
  number  = {1},
  issue   = {Spring},
  url     = {http://web.mit.edu/asf/www/PopularScience/Friedman_BrainsAndTuringMachines_2002.pdf},
  urldate = {2019-06-19},
}

Answer 2

Cite it as @Misc, and give as much detail as you can get (e.g., URL where to find it, where it is cited, ...).