I often google vocabulary lists that other teachers have compiled and shared for use in the classroom. I put them all together and then whittle down the list to find words that will be useful in the lives of my students. Of course, when teaching these words in the context of the book, it is nice to know where exactly the words are used and in what context.
Amazon's relatively new feature, Search Inside the Book, is perfect for this. When signed-in, you can search the text of any book enrolled (most classics) and find the passage you are looking for.
How do you use it? Once you have your word list (I don't recommend teaching any more than 10 words (and that's a lot) per week), go to the page for the edition of the book you own. Below the image for the cover will be a series of links, one of them labeled "Search Inside This Book." You can use the search bar on the left of the pop-up window to search for the word. If you are not satisfactorily logged-in, you will be prompted to log-in and then returned to the Search Inside The Book page.
I used this feature to find all of the 14 words on my The Things They Carried word list, then highlighted and flagged them in my physical book. Teaching vocabulary in the context of a written work is almost-always going to yield better results than picked an arbitrary list of words to know.
Happy searching!