?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Lehmann%2C+Timothy&rft.aufirst=Timothy&rft.aulast=Lehmann&rft.title=Developing+an+abstract+understanding+of+unit+iteration+through+problem+solving&rft.date=21+November+2018&rft.genre=bookitem