If you find materials on the internet you have to be extra careful and critical. Everyone can upload texts on the internet and there is no guarantee that what you find is usable in an academic paper. A good idea is to check the URL (the web-address at the top of the page) and see if the material came from a reliable source.
Even when the text you want to use is reliable and scientifically sound, it is still a good idea to be critical.
Posing these questions is a good way to approach your material and find out what the texts' strengths and weaknesses are:
The questions at the bottom of this page are based on the book Opgaveskrivning på videregående uddannelser - en lærerbog by Lotte Rienecker and Peter Stray Jørgensen. Samfundslitteratur, 1999.