If the reader wants to know the details of EMIRT, please refer to the paper: Estimation for Item Response Models using the EM Algorithm for Finite Mixtures.
@article{woodruff1996estimation,
title={Estimation of Item Response Models Using the EM Algorithm for Finite Mixtures.},
author={Woodruff, David J and Hanson, Bradley A},
year={1996},
publisher={ERIC}
}