I am writing an IEEE conference paper (IEEE Photonics Society Summer Topicals) and I sometimes see that shortened version of citations are used, without the title of paper. For example, something like
 J. Sun, J. Zeng, and N. M. Litchinitser, Opt. Express 21, 2013, 14975- 14981.
 M. I. Shalaev, Z. A. Kudyshev, and N. M. Litchinitser, Opt. Lett. 38, 2013, 4288-4291
What is this style of citation called? I would like to use this style of citation in my paper to save space.