BibTex format
@article{Sheppard:1997:10.1080/09500349708230696,
author = {Sheppard, CJR and Torok, P},
doi = {10.1080/09500349708230696},
journal = {JOURNAL OF MODERN OPTICS},
pages = {803--818},
title = {Efficient calculation of electromagnetic diffraction in optical systems using a multipole expansion},
url = {http://dx.doi.org/10.1080/09500349708230696},
volume = {44},
year = {1997}
}