What is the role of public relations in the formulation of the marketing mix?

What is the role of public relations in the formulation of the marketing mix? Provide specific examples to support your response.Sources (If you want to use)https://ebookcentral-proquest-com.ezproxy.snhu.edu/lib/snhu-ebooks/reader.action?docID=1652024https://eds-b-ebscohost-com.ezproxy.snhu.edu/eds/detail/detail?vid=0&sid=a54d0513-23ba-4764-8998-0a551a7e611d%40pdc-v-sessmgr02&bdata=JnNpdGU9ZWRzLWxpdmUmc2NvcGU9c2l0ZQ%3d%3d#AN=edsbig.A206693009&db=edsbig