The maximum weight for a U.S. semi truck and full trailer is 80,000 pounds spread over 18 conventional wheels. Out in the wide-open spaces of Australia, however, road trains can have four trailers and weigh in excess of 300,000 pounds.
Types of academic source. Sources such as newspaper articles, magazine articles, opinion pieces, and websites are not commonly academic, although there are some exceptions. Many journal articles and reports can be found online, for example. Academic journals are very different from popular magazines, although they bear several similarities.
Sources of information are often categorized as primary or secondary depending upon their originality. Primary Sources. A primary source provides direct or firsthand evidence about an event, object, person, or work of art. Primary sources provide the original materials on which other research is based and enable students and other researchers to get as close as possible to what actually happened during a particular event or time period.