This source is a study guide on Kuhn's structure of science made by proffesor Frank Pajares; it seems reliable as it comes from a .edu which are usually extracted from a university or college. its strength is that it is very easy and simple to follow and still gives you pretty good information. one thing that could mabey change is more information should be given in detail.

This webpage gives a detailed background on no only popper but also his ideas and views. the source seems reliable as i found it on Jstore and is the review/report on a book on popper.