Links on OS development

Assembly Tutorial on Protected Mode:
http://my.execpc.com/CE/AC/geezer/os/pm.htm
http://www.faqs.org/faqs/assembly-language/x86/general/part1/section-13.html
http://x86.ddj.com/articles/pmbasics/tspec_a1_doc.htm
http://members.tripod.com/protected_mode/prashant/protmode.html
OS Development:
http://www.azillionmonkeys.com/qed/tech.shtml
http://www.osdev.org/osfaq2/
http://www.nondot.org/sabre/os/articles
http://www.nondot.org/sabre/os/files/Misc/vade.mecum.2.pdf
http://users.evtek.fi/~tk/rt_html/TOUR.HTM
http://www.osdever.net/bkerndev/index.php
http://www.osdever.net/tutorials/brunmar/tutorial_01.php
On executable file (ELF):
http://www.linuxjournal.com/article/1059
http://www.linuxjournal.com/article/1060
http://www.linuxforums.org/misc/understanding_elf_using_readelf_and_objdump.html
The best FAQ on OS development:
http://my.execpc.com/~geezer/temp/qna.txt