I have a book on the public opinion of the Yishuv (Jewish population of  Eretz-Yisrael) toward the Civil War in Spain in 1936-1939.

One subject heading would be:

Spain--History--Civil War, 1936-1939--Foreign public opinion, Palestinian  (Jewish)   [or Jewish Palestinian]

other headings will be:
Jews--Palestine--Attitudes
and
Public opinion--Palestine

Could one use the first heading?

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Answer:

My recommendation is that you not apply any national qualifier to the heading:

Spain--History--Civil War, 1936-1939--Foreign public opinion.

The nationality is brought out anyway in the additional heading:

Jews--Palestine--Attitudes.

I confirmed with CPSO that the use of "Palestinian Jewish" (or other variations) as an adjectival form is not valid.   In LCSH one cannot create a compound adjective unless a heading for the corresponding compound group exists.

Lenore Bell