For a research article, Carlos is studying the latest treatments for antibiotic-resistant diseases, which are caused by pathogens that are immune to most antibiotics. So far, his primary source is a textbook that was updated five years ago. Carlos should, use the textbook as the primary source even though the information is dated. examine peer-reviewed journals because there is likely new information available. search the Internet for pharmaceutical websites that have information about treatment. check magazines and newspapers to see if they have more recent articles to use as sources.