Theoretical foundations of the so-called cross-reference structures

1 Definitions of cross-reference structures 5.1 When is a cross-reference possible and ap2 What is a cross-reference ? propiate ? 3 Preliminary cross-reference conditions (1) 5.2 How many cross-references ? 3.1 Preliminary cross-reference conditions (2) 5.3 The concepts of explicit and implicit cross4 Distribution structures references 4.1 Distribution of knowledge elements and 5.4 The position of cross-references their mutual relations 6 Definitions of lexicographic structures 5 Distribution structures and cross-references 7 Do cross-references form a structure ? 8 Bibliography