http://g7ee5otfyict57k24vjujuqzi6pd7iwvnsry2mt3svsgwzn6o6iynsad.onion/popets/2016/popets-2016-0036.php
This connection was previously observed by Henry, Huang, and Goldberg (NDSS 2013), who used ramp schemes to construct efficient “batch queries” with which clients can fetch several database records for the same cost as fetching a single record using a standard, non-batch query.