When it comes to research methodology for my writing services, I take this practice very seriously. Even with subjects that I have a piece of knowledge, I still research before starting any writings.
Type of Sources
I use respectable and trustworthy sources if possible academic sources and I always include the citation sources with my writing services and infographic creation services. I do not use unreliable sources or competitors sources.
Of course, in the end, it will be your choice to publish my referring sources, but that is a decision for you to make.