@techreport {DRP-200801-Keith,
type = {Directed Research Project},
author = {Daniel B. Keith},
title = {Control Operators: Issues of Expressibility},
institution = {University of Oregon, Computer and Information Sciences Department},
number = DRP-200801-Keith,
month = 1,
year = 2008,
note = {Available at \url{https://www.cs.uoregon.edu/Reports/DRP-200801-Keith.pdf}},
}