I will be happy to direct you to two works by William of Ockham that have been published (somewhat recently) as an English translation, but I am not making any claim that either of these should be classified as among his most important works. Both of these are from the series, Cambridge Texts in the History of Political Thought. I think you can purchase these on Amazon.

William of Ockham, A Short Discourse on the Tyrannical Government, trans. John Kilcullen (Cambridge: Cambridge University Press, 1992), 215 pages.

William of Ockham, A Letter to the Friars Minor and Other Writings, trans. John Kilcullen (Cambridge: Cambridge University Press, 1995), 393 pages.

You might want to acquire this book - Paul Vincent Spade, The Cambridge Companion to Ockham (Cambridge: Cambridge University Press, 1999), 420 pages.

These are books from my own library.

DTK

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Sola Scriptura est norma normans non normata
David T. King, pastor
Christ Presbyterian Church (OPC)
Elkton, Maryland
Augustine (354-430): Therefore what He [i.e., Christ] has deigned to speak to us, we ought to believe that He meant us to understand. But if we do not understand He, being asked, gives understanding, who gave His Word unasked. NPNF1: Vol. VII, Tractates on John, Tractate XXII, §1.