Hash Tables ....

i have a project , about hash tables ,
i have to reference all courses in my university with credits etc .. and i am supposed to use Hash Tables ...
the thing is i did not attend the lecture where the professor explained it ...
and the book is horrible .. anyone has any idea where i can get some documentation ?
(on the net) or if vb contains a hash "class" ??

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- regards -
- razzaj -