Why is it bad to include new information in a summary?

Look up the information for as many of these sources aspossible and write the works cited entry for each one. (you may make up dates and editions where necessary for the purposes of this exercise.)1. mark twain’s  the mysterious stranger2. a dictionary entry for the word  castigation  from  merriam-webster  (any edition)3. an article in  cosmopolitan  magazine by jennifer grant called “all you need to know”4. an encyclopedia entry for the name “geraldine ferraro” from  world book encyclopedia5. a website article titled “welcome to oz” with no listed author or publisher and no corporate affiliation

What element of medieval literature does the disappearance of the sword into the lake represent?

Someone get back to me , i really don’t get this