@article{Bruls2015,
  author    = {George J. C. L. Bruls},
  title     = {Exact formulas for a thin-lens system with an arbitrary number of lenses},
  journal   = {Optik},
  volume    = {126},
  number    = {6},
  pages     = {659 -- 662},
  doi       = {10.1016/j.ijleo.2015.01.035},
  year      = {2015},
}