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http://inst.eecs.berkeley.edu/~selfpace/studyguide/9C.sg/Output/ADTs.in....
https://www.haskell.org/haskellwiki/Abstract_data_type
http://xlinux.nist.gov/dads/HTML/abstractDataType.html
http://cse.iitkgp.ac.in/pds/notes/ADT.html
http://pages.cs.wisc.edu/~hasti/cs367-1/readings/Introduction/index.html
10th grade
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