Schwarz, Christian Algorithms and Complexity, MPI for Informatics, Max Planck Society;
Smid, Michiel Algorithms and Complexity, MPI for Informatics, Max Planck Society;
https://rdcu.be/dwOoa (Verlagsversion)
Schwarz, C., Smid, M., & Snoeyink, J. (1994). An Optimal Algorithm for the On-line Closest-pair Problem. Algorithmica, 12(1), 18-29. doi:10.1007/BF01377181.