@article(Cha13,
 author       = {Saloua Chatti and Fabien Schang},
 year         = {2013},
 title        = {The Cube, the Square and the Problem of Existential Import},
 journal      = {History and Philosophy of Logic},
 volume       = {34},
 number       = {2},
 pages        = {101--132},
 doi          = {10.1080/01445340.2013.764962},
)
@article(Eng69,
 author       = {George Englebretsen},
 year         = {1969},
 title        = {Knowledge, Negation, and Incompatility},
 journal      = {The Journal of Philosophy},
 volume       = {66},
 number       = {18},
 pages        = {580--585},
 doi          = {10.2307/2023970},
)
@article(Eng80,
 author       = {George Englebretsen},
 year         = {1980},
 title        = {On Propositional Form},
 journal      = {Notre Dame Journal of Formal Logic},
 volume       = {21},
 number       = {1},
 pages        = {101--110},
 doi          = {10.1305/ndjfl/1093882942},
)
@article(Eng84,
 author       = {George Englebretsen},
 year         = {1984},
 title        = {Opposition},
 journal      = {Notre Dame Journal of Formal Logic},
 volume       = {25},
 number       = {1},
 pages        = {79--84},
 doi          = {10.1305/ndjfl/1093882942},
)
@article(Eng86,
 author       = {George Englebretsen},
 year         = {1986},
 title        = {Singular/General},
 journal      = {Notre Dame Journal of Formal Logic},
 volume       = {27},
 number       = {1},
 pages        = {104--107},
 doi          = {10.1305/ndjfl/1093636528},
)
@article(Eng88,
 author       = {George Englebretsen},
 year         = {1988},
 title        = {A note on Leibniz's wild quantity thesis},
 journal      = {Studia Leibnitiana},
 volume       = {20},
 number       = {1},
 pages        = {87--89},
 url          = {https://www.jstor.org/stable/40694095},
)
@article(Eng16b,
 author       = {George Englebretsen},
 year         = {2016},
 title        = {Fred Sommers' Contributions to Formal Logic},
 journal      = {History and Philosophy of Logic},
 volume       = {37},
 number       = {3},
 pages        = {269--291},
 doi          = {10.1080/01445340.2016.1186884},
)
@incollection(Eng16a,
 author       = {George Englebretsen},
 year         = {2016},
 title        = {La quadrature du carr\'e},
 editor       = {Amirouche Moktefi and Alessio Moretti and Fabien Schang},
 booktitle    = {Let's be Logical},
 publisher    = {College Publications},
 address      = {London},
 pages        = {49--64},
)
@article(Hum13,
 author       = {Lloyd Humberstone},
 year         = {2013},
 title        = {Logical relations},
 journal      = {Philosophical Perspectives},
 volume       = {27},
 number       = {1},
 pages        = {175--230},
 doi          = {10.1111/phpe.12021},
)
@article(Hum20,
 author       = {Lloyd Humberstone},
 year         = {2020},
 title        = {Explicating Logical Independence},
 journal      = {Journal of Philosophical Logic},
 volume       = {49},
 pages        = {135--218},
 doi          = {10.1007/s10992-019-09516-w},
)
@book(Key07,
 author       = {John Neville Keynes},
 year         = {1906},
 title        = {Studies and Exercises in Formal Logic},
 edition      = {4},
 publisher    = {MacMillan and Co. Limited},
 url          = {https://www.gutenberg.org/ebooks/59590},
)
@article(Rea15,
 author       = {Stephen Read},
 year         = {2015},
 title        = {Aristotle and \L ukasiewicz on Existential Import},
 journal      = {Journal of the American Philosophical Association},
 volume       = {1},
 number       = {3},
 pages        = {535--544},
 doi          = {10.1017/apa.2015.8},
)
@article(San68,
 author       = {David H. Sanford},
 year         = {1968},
 title        = {Contraries and subcontraries},
 journal      = {No\^{u}s},
 volume       = {2},
 pages        = {95--96},
 doi          = {10.2307/2214419},
)