What is the purpose of a signal phrase 1.to ponit out an internal citation to the reader 2.to call attention to plagiarism in information text 3.to indicate the end of text and start of citations

i would like to compare these two interpretations of the crucible : 1) eric christ's interretation and wade bradford's interpretation. the main differences between there interretaions is that in the first one you can notice direct link to joseph mccarthy whereas the second one represents how the town is filled with hysteria.the second interpretation shows that author believes that the story   about puritan town in salem is based on actual events while the first example shows the sencible reference to sort of bias.

showing or suffering from nervousness, fear, or a lack of confidence