Chapter I General Introduction Section I: Conception of IEL Section II: Sources of iel Section II: Basic Principles of IEL Section IV: Relationship Between IEL and other legal branchesChapter I General Introduction Section Ⅰ：Conception of IEL Section Ⅱ: Sources of IEL Section Ⅲ：Basic Principles of IEL Section Ⅳ：Relationship Between IEL and other legal branches