+@Article{dirac28,
+ author = "P. A. M. Dirac",
+ title = "The Quantum Theory of the Electron",
+ volume = "117",
+ number = "778",
+ pages = "610--624",
+ year = "1928",
+ doi = "10.1098/rspa.1928.0023",
+ URL = "http://rspa.royalsocietypublishing.org/content/117/778/610.short",
+ eprint = "http://rspa.royalsocietypublishing.org/content/117/778/610.full.pdf+html",
+ journal = "Proceedings of the Royal Society of London. Series A",
+ notes = "spin orbit origin, relativistic quantum theory",
+}
+
+@Article{kleinman80,
+ title = "Relativistic norm-conserving pseudopotential",
+ author = "Leonard Kleinman",
+ journal = "Phys. Rev. B",
+ volume = "21",
+ issue = "6",
+ pages = "2630--2631",
+ year = "1980",
+ month = mar,
+ doi = "10.1103/PhysRevB.21.2630",
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.21.2630",
+ publisher = "American Physical Society",
+ notes = "first relativistic pseudopotential",
+}
+
+@Article{bachelet82,
+ title = "Relativistic norm-conserving pseudopotentials",
+ author = "Giovanni B. Bachelet and M. Schl{\"u}ter",
+ journal = "Phys. Rev. B",
+ volume = "25",
+ issue = "4",
+ pages = "2103--2108",
+ year = "1982",
+ month = feb,
+ doi = "10.1103/PhysRevB.25.2103",
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.25.2103",
+ publisher = "American Physical Society",
+}
+
+@Article{hybertsen86,
+ title = "Spin-orbit splitting in semiconductors and insulators
+ from the \textit{ab initio} pseudopotential",
+ author = "Mark S. Hybertsen and Steven G. Louie",
+ journal = "Phys. Rev. B",
+ volume = "34",
+ issue = "4",
+ pages = "2920--2922",
+ year = "1986",
+ month = aug,
+ doi = "10.1103/PhysRevB.34.2920",
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.34.2920",
+ publisher = "American Physical Society",
+ notes = "spin orbit pseudopotential formulation",
+}
+
+@Article{naveh07,
+ title = "Real-space pseudopotential method for spin-orbit
+ coupling within density functional theory",
+ author = "Doron Naveh and Leeor Kronik and Murilo L. Tiago and
+ James R. Chelikowsky",
+ journal = "Phys. Rev. B",
+ volume = "76",
+ issue = "15",
+ pages = "153407",
+ numpages = "4",
+ year = "2007",
+ month = oct,
+ doi = "10.1103/PhysRevB.76.153407",
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.76.153407",
+ publisher = "American Physical Society",
+ notes = "real space spin orbit pseudopotential implementation",
+}