How do I go about citing a summary of a book? I am writing a political science paper and I need to cite a paper that is a summary/analysis of the ideas of a book, so would my in text citation be of the original book or of the summary? And would I include both in my works cited page? I'm using MLA format.

How does this excerpt develop the central idea that espionage during the civil war was often carried out by untrained citizens? it enhances the reader’s understanding by explaining why training was unnecessary. it changes the reader’s perception of what information a spy was able to obtain. it explains an ordinary person’s motivation for conducting espionage against the enemy. it adds moral complexity to espionage, due to the use of secret and dangerous methods.