There was similar complaint before. Here are the links there:

What's New in KML 2.1? Tutorial and Overview :: http://earth.google.com/kml/kml_21tutorial.html

KML 2.1 Specification (Beta) :: http://earth.google.com/kml/kml_tags_21.html
KML 2.1 Specification (Beta- PDF version) :: http://earth.google.com/kml/kml_tags_21.pdf


Introduction to KML 2.0 :: http://earth.google.com/kml/kml_intro.html

KML 2.0 Specification :: http://earth.google.com/kml/kml_tags.html

KML 2.0 Tutorial :: http://earth.google.com/kml/kml_tut.html

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