Pistemology / Essay Question: Is knowledge closed under known entailment?

Reading:
*Nozick, R. 1981 Philosophical Explanations. Cambridge MA: Harvard University Press, pp172-85, 197-217. Also reprinted as Chapter 21 of Epistemology.

The above readings are the required readings for the essay, I will provide all these readings for the writer. Please use these readings as references and add any others if available. Thank you