Here are a few links i found on Google.
Try it yourself you can find many more.
Datasheets
http://www.national.com/ds/CD/CD4093BC.pdf
http://users.pandora.be/on4ldz/Lightning/data_sheet/CD4093.pdf
http://noel.feld.cvut.cz/hw/motorola/books/dl131/pdf/mc14093brev3.pdf
Application notes
http://online.sfsu.edu/~sfranco/CoursesAndLabs/Labs/453LabsPDF/453Lab3.pdf
http://hyperphysics.phy-astr.gsu.edu/HBASE/electronic/schmitt.html
http://www.ee.ttu.edu/lab/robot/hyster.htm
http://en.wikipedia.org/wiki/Schmitt_trigger
http://www.musicfromouterspace.com/analogsynth/mmlogic.html
http://www.answers.com/topic/schmitt-trigger