@article{gibbons-2009-the, title={The essence of the
                    <scp>Iterator</scp>
                    pattern}, volume={19}, ISSN={1469-7653}, url={http://dx.doi.org/10.1017/s0956796809007291}, DOI={10.1017/s0956796809007291}, number={3-4}, journal={Journal of Functional Programming}, publisher={Cambridge University Press (CUP)}, author={GIBBONS, JEREMY and OLIVEIRA, BRUNO C. d. S.}, year={2009}, month=July, pages={377–402} }