Where can I find a copy of Paul Kiparsky's How abstract is phonology? written in 1968?
I haven't found any online/digital versions, but I came upon the places where it's reprinted. You should be able to get it in your library or via interlibrary loan, I suppose:
Kiparsky, Paul. 1968. How Abstract Is Phonology? Bloomington, Indiana: Indiana University Linguistics Club.
Reprinted as a section (pp. 5-56) of: Kiparsky, Paul. 1973. “Phonological Representations.” In: Three Dimensions of Linguistic Theory, edited by Osamu Fujimura, Donald L Smith, S. I Harada, and Julie. B Lovins. Tokyo: Tokyo Institute for Advanced Studies of Language.
Kiparsky, Paul. 1982. Explanation in Phonology. Dordrecht: Foris. Pp. 119-163.