Epistemology is the study of knowledge and justified belief. As the study of knowledge, epistemology is concerned with the following questions: What are the necessary and sufficient conditions of knowledge? What are its sources? What is its structure, and what are its limits? As the study of justified belief, epistemology aims to answer questions such as: How we are to understand the concept of justification? What makes justified beliefs justified? Is justification internal or external to one's own mind? 

Here is a series of studied philosophers and my interpretation of their thoughts. 

Enmmanuel Kant.
Georg Wilhelm Friedrich Hegel.
Martin Heidegger.
David Hume.
Jean-Jacques Rousseau.