@inproceedings(Cao06,
 author       = "Z. Cao",
 year         = "2006",
 title        = "More on Bisimulations for Higher Order $\pi $-Calculus",
 editor       = "L. Aceto and A. In{\'g}olfsd{\'o}ttir",
 booktitle    = "Proceedings of FOSSACS2006",
 series       = "LNCS",
 volume       = "3921",
 pages        = "63--78",
 doi          = "10.1007/11690634\_5",
 note         = "Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2006, Vienna, Austria, March 25-31, 2006.",
)
@article(JR05,
 author       = "A. Jeffrey and J. Rathke",
 year         = "2005",
 title        = "Contextual equivalence for higher-order pi-calculus revisited",
 journal      = "Logical Methods in Computer Science",
 volume       = "1(1:4)",
 doi          = "10.2168/LMCS-1(1:4)2005",
)
@inproceedings(LPSS10,
 author       = "I. Lanese and J. A. P\'{e}rez and D. Sangiorgi and A. Schmitt",
 year         = "2010",
 title        = "On the Expressiveness of Polyadic and Synchronous Communication in Higher-Order Process Calculi",
 booktitle    = "Proceedings of ICALP 2010",
 series       = "LNCS",
 publisher    = "Springer Verlag",
 pages        = "442--453",
 doi          = "10.1007/978-3-642-14162-1\_37",
)
@article(LPSS10a,
 author       = "I. Lanese and J. A. P\'{e}rez and D. Sangiorgi and A. Schmitt",
 year         = "2011",
 title        = "On the Expressiveness and Decidability of Higher-Order Process Calculi",
 journal      = "Information and Computation",
 volume       = "209(2)",
 pages        = "198--226",
 doi          = "10.1016/j.ic.2010.10.001",
)
@inproceedings(LPSS08,
 author       = "I. Lanese and J.A. Perez and D. Sangiorgi and A. Schmitt",
 year         = "2008",
 title        = "On the Expressiveness and Decidability of Higher-Order Process Calculi",
 booktitle    = "Proceedings of the 23rd Annual IEEE Symposium on Logic in Computer Science (LICS 2008)",
 publisher    = "IEEE Computer Society",
 pages        = "145--155",
 doi          = "10.1109/LICS.2008.8",
 note         = "Journal version in \cite {LPSS10a}",
)
@article(Mil92,
 author       = "R. Milner",
 year         = "1992",
 title        = "Functions as Processes",
 journal      = "Mathematical Structures in Computer Science",
 volume       = "2(2)",
 pages        = "119--141",
 doi          = "10.1017/S0960129500001407",
 note         = "Research Report 1154, INRIA, Sofia Antipolis, 1990",
)
@phdthesis(San92,
 author       = "D. Sangiorgi",
 year         = "1992",
 title        = "Expressing Mobility in Process Algebras: First-order and Higher-order Paradigms",
 type         = "Phd thesis",
 school       = "University of Edinburgh",
)
@inproceedings(San92a,
 author       = "D. Sangiorgi",
 year         = "1992",
 title        = "From $\pi $-Calculus to Higher-Order $\pi $-Calculus---and Back",
 booktitle    = "Proceedings of TAPSOFT '93",
 series       = "LNCS",
 volume       = "668",
 publisher    = "Springer Verlag",
 pages        = "151--166",
 doi          = "10.1007/3-540-56610-4\_62",
)
@article(San94,
 author       = "D. Sangiorgi",
 year         = "1996",
 title        = "Bisimulation for Higher-order Process Calculi",
 journal      = "Information and Computation",
 volume       = "131(2)",
 pages        = "141--178",
 doi          = "10.1006/inco.1996.0096",
 note         = "Preliminary version in proceedings of PROCOMET'94 (IFIP Working Conference on Programming Concepts, Methods and Calculi), pages 207-224, North Holland, 1994",
)
@article(San96,
 author       = "D. Sangiorgi",
 year         = "1996",
 title        = "Pi-calculus, Internal Mobility and Agent-Passing Calculi",
 journal      = "Theoretical Computer Science",
 volume       = "167(2)",
 doi          = "10.1016/0304-3975(96)00075-8",
 note         = "Extracts of parts of the material contained in this paper can be found in the Proceedings of TAPSOFT'95 and ICALP'95",
)
@article(San98,
 author       = "D. Sangiorgi",
 year         = "1998",
 title        = "On the Bisimulation Proof Method",
 journal      = "Mathematical Structures in Computer Science",
 volume       = "8(6)",
 pages        = "447--479",
 doi          = "10.1017/S0960129598002527",
 note         = "An extended abstract in Proceedings of MFCS'95, LNCS 969, pp. 479-488, Springer Verlag",
)
@article(SKS11,
 author       = "D. Sangiorgi and N. Kobayashi and E. Sumii",
 year         = "2011",
 title        = "Environmental bisimulations for higher-order languages",
 journal      = "ACM Transactions on Programming Languages and Systems",
 volume       = "33(1)",
 pages        = "5",
 doi          = "10.1145/1889997.1890002",
)
@book(SW01a,
 author       = "D. Sangiorgi and D. Walker",
 year         = "2001",
 title        = "The Pi-calculus: a Theory of Mobile Processes",
 publisher    = "Cambridge Universtity Press",
)
@phdthesis(Tho90,
 author       = "B. Thomsen",
 year         = "1990",
 title        = "Calculi for Higher Order Communicating Systems",
 type         = "Phd thesis",
 school       = "Department of Computing, Imperial College",
)
@article(Tho93,
 author       = "B. Thomsen",
 year         = "1993",
 title        = "Plain {CHOCS}, a Second Generation Calculus for Higher-Order Processes",
 journal      = "Acta Informatica",
 volume       = "30(1)",
 pages        = "1--59",
 doi          = "10.1007/BF01200262",
)
@inproceedings(VD98,
 author       = "J.-L. Vivas and M. Dam",
 year         = "1998",
 title        = "From Higher-Order Pi-Calculus to Pi-Calculus in the Presence of Static Operators",
 booktitle    = "Proceedings of the 9th International Conference on Concurrency Theory",
 series       = "LNCS",
 volume       = "1466",
 pages        = "115--130",
 doi          = "10.1007/BFb0055619",
 note         = "Nice, France, September 8-11, 1998",
)
@article(Xu12,
 author       = "Xian Xu",
 year         = "2012",
 title        = "Distinguishing and Relating Higher-order and First-order Processes by Expressiveness",
 journal      = "Acta Informatica",
 volume       = "49(7-8)",
 pages        = "445--484",
 doi          = "10.1007/s00236-012-0168-9",
)