The process and sources described above will provide you with most of the available legislative history material provided by the state.
The following titles contain helpful chapters on researching legislative history in Illinois:
Legislative Reference Bureau, Researching Legislative History
Wojcik, Mark E. Illinois Legal Research. Durham, NC.: Carolina Academic Press (2009). KFI1275 W65 2009 Reserve and Academic Success. See Chapter 4 on Statutes.
Wendt, Laurel. Illinois Legal Research Guide. 2nd ed. KFI 1275 .W46 2006 Reserve.
If you have any further questions about the legislative history materials feel free to ask a reference librarian for assistance.