Hey gabriel,
I have just started reading and getting to know what this EWB challenge is about for a project for a unit i am studying in university. If you are in university or studying something academically the way to tell for credible sources you use the CRAAP system a quick google search will help you understand and learn how to find credible sources.
https://libguides.cdu.edu.au/c.php?g=167948&p=1103060
quick read through this will help heaps.
otherwise, if you are really finding it hard to find credible sources for a specific design area, you got another 6-7 to choose from just choose something else?.
Kind Regards,
Omar