We talk about secondary written sources when there is no direct contact between the source’s author and the events or state of affairs, but when there is at least one intermediary between them. Therefore, secondary written sources are accounts that draw their knowledge from the preserved and accessible accounts. Professional and scientific literature is generally intended for people who already possess certain prior expert knowledge. Good scientific and professional literature is written by authors who mention the exact sources or research studies on which their findings are based. Moreover, the author has to provide information as yet unknown to science or which cannot be proved. Such scientific descriptions require a great effort from the reader as they cite many sources. Popular science descriptions, on the other hand, do not. They are intended for a wider audience of »curious laypeople«. Such works are characterised by an interesting narrative technique, which does not primarily impart findings about historical discoveries or interpretations, but rather provides the chance to relive and become engrossed in the narrative itself. Its main advantage is that it presents complex matters in a way that is easier to understand.