Bibtex Entry:

@article{ToN-SDN-upgrade,
 author = "Konstantinos Poularakis and George Iosifidis and Georgios Smaragdakis and Leandros Tassiulas",
 title = {{Optimizing Gradual SDN Upgrades in ISP Networks}},
 journal = {{IEEE/ACM Transactions on Networking}},
 volume={27},
 number={1},
 pages={288--301},
 month={February},
 year = {2019}
}