@incollection{choi2018-mobile,
  author = {Choi, Jeongil and Park, Youngju and Kim, Yonghee},
  title = {A Study on the Efficiency of Global Major Mobile Operators},
  booktitle = {Software Engineering Research, Management and Applications (Studies in Computational Intelligence, vol. 789)},
  year = {2019},
  volume = {789},
  pages = {129--141},
  publisher = {Springer, Cham},
  doi = {10.1007/978-3-319-98881-8_9}
}