Quality sources refer to reliable and trustworthy information or materials that are used as references in a particular context. These sources are usually created or produced by experts in a particular field, and are considered to be accurate, credible, and up-to-date. Quality sources can include academic journals, books written by reputable authors, government reports or statistics, and respected news outlets. Using quality sources helps to ensure that the information or data being presented is accurate and reliable, which can be important in various contexts such as research, decision-making or problem solving.