If using biblatex and biber is an option (cf. this post to get started), then I would recommend using the booklet or report entry types.
Per the documentation:
booklet
A book-like work without a formal publisher or sponsoring institution.
Use the field howpublished to supply publishing information in free
format, if applicable. The field type may be useful as well.
Required fields: author/editor, title, year/date
Optional fields: subtitle, titleaddon, language, howpublished, type, note, location, chapter, pages, pagetotal, addendum, pubstate, doi,
eprint, eprintclass, eprinttype, url, urldate
report
A technical report, research report, or white paper published by a
university or some other institution. Use the type field to specify
the type of report. The sponsoring institution goes in the institution
field.
Required fields: author, title, type, institution, year/date
Optional fields: subtitle, titleaddon, language, number, version, note, location, month, isrn, chapter, pages, pagetotal, addendum,
pubstate, doi, eprint, eprintclass, eprinttype, url, urldate
A possible example for your entry could be:
\RequirePackage{filecontents}
\begin{filecontents}{mybib.bib}
@misc{sutherland-notes-misc,
author = "Andrew Sutherland",
title = "{Elliptic Curves}",
note = "URL: \url{https://math.mit.edu/classes/18.783/2015/lectures.html}.
Last visited on 2017/07/01",
year = 2015,
}
@booklet{sutherland-notes-booklet,
author = "Andrew Sutherland",
title = "{Elliptic Curves}",
note = "URL: \url{https://math.mit.edu/classes/18.783/2015/lectures.html}.
Last visited on 2017/07/01",
year = 2015,
}
@report{sutherland-notes-report,
author = "Andrew Sutherland",
title = "{Elliptic Curves}",
note = "URL: \url{https://math.mit.edu/classes/18.783/2015/lectures.html}.
Last visited on 2017/07/01",
year = 2015,
institution = "Massachusetts Institute of Technology, Department of Mathematics"
}
\end{filecontents}
\documentclass{article}
\usepackage{biblatex}
\bibliography{mybib}
\begin{document}
\cite[14. Ordinary and supersingular curve]{sutherland-notes-misc}, \cite[14. Ordinary and supersingular curve]{sutherland-notes-booklet}, \cite[14. Ordinary and supersingular curve]{sutherland-notes-report}
\printbibliography
\end{document}
Note that the three entries will be displayed similarly:
