You really need to buy a copy of the book,
U.S. International Postal Rates, 1872-1996, by Anthony S. Wawrukiewicz & Henry W. Beecher, if you plan to collect and understand covers like these.
Copies can be found on eBay, and I believe the APS bookstore has these at a reasonable price.
For Palestine, here is the Page for Air Mail rates as an example.
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I cannot imagine anyone who collects US postal history not having a copy of both this and the domestic rate book on their desk.
Mike