Qing Ye Liang Cheng DTP: Double-Pairwise Time Protocol for Disruption Tolerant Networks. 345-352 2008 ICDCS https://doi.org/10.1109/ICDCS.2008.73 https://doi.ieeecomputersociety.org/10.1109/ICDCS.2008.73 conf/icdcs/2008 db/conf/icdcs/icdcs2008.html#YeC08