There are several sources in which one may turn to in order to establish a well-founded idea, information, and knowledge towards a given topic. From this item, books were collectively identified as the first source for Jamal's science essay.
The second one could be the information found in the internet. These information have lately became very accessible considering that one could directly upload/download information. The tricky part here is to identify which sources in the internet are reliable and which are not.