Reference to the unpublished lecture notes I doubt about the following situation.
There is a kind of lecture notes, which contains really valuable examples on which I want make a reference from my paper (I cite some of them and reuse some of them).
But this work wasn't officially published, and it is not listed in the list of the works in the CV of the author. The only one place where this document appears is this link:

https://pdfs.semanticscholar.org/95a3/cb63b80c3416879d534f41eedcd174b40159.pdf

So what the proper way to deal with this situation? Give a link like on web-resource as MISC or UNPUBLISHED or do not make reference at all?

At the moment citation of this work looks like:

M. Kanazawa, Context-free tree grammars, SemanticScholar, URL https://pdfs.semanticscholar.org/95a3/cb63b80c3416879d534f41eedcd174b40159.pdf, 2012. 

which doesn't look very nice.

HINT: I'm not asking for a specific TeX or BibTex advice! 
Below just a convenient formal view of the reference which I'm going to put.

@MISC {kanazawamakoto2012,
    author   = "Kanazawa, Makoto",
    title    = "Context-free tree grammars",
    HOWPUBLISHED= {SemanticScholar},
    month    = "feb",
    year     = "2012",
    URL = "https://pdfs.semanticscholar.org/95a3/cb63b80c3416879d534f41eedcd174b40159.pdf"
}
In APA (6th) citation style, it would look like this:

Kanazawa, M. (2012). Context-free tree grammars. Lecture, Place/University. Retrieved 4 May 2017, from https://pdfs.semanticscholar.org/95a3/cb63b80c3416879d534f41eedcd174b40159.pdf

The Place/University should be corrected. Could be SemanticScholar.

Nevertheless, I'd check (before citing this lecture note) whether the information you want to cite is included in one of the given references.

Note: Since the desired citation style is not clear, I used APA as default. I can change the citation style, if the desired one is added to the question.