Didn't you already post this ?
I'd do something like this depending on how different each level is
SectionID (primary Key)
ParentSectionID (foreign key)
data would be stored like this :
1 0 Preface
2 0 Introduction
3 2 -subtitle1
4 2 -subtitle2
5 0 Chapter 1
6 5 -subtitle 1
7 5 -subtitle 2...
To get all the top level sections you would do
SELECT * FROM tbl_Sections WHERE ParentSectionId = 0
An alternative aproach where you want differnt information depending on the level would be to havea separate table for the top level and sub levels.