BrianMacWhinney, AndrejMalchukov & EdithMoravcsik(editors). Competing motivations in grammar and usage. Oxford: Oxford University Press, 2014. xxi+445 pp. ISBN 978-0-19-870984-8
Du Bois, John. 1985. Competing motivations. In John Haiman (editor), Iconicity in syntax. Proceedings of a symposium on iconicity in syntax. Amsterdam and Philadelphia: Benjamins. 343–365.
Gabelentz, Georg von der. 1901. Die Sprachwissenschaft, ihre Aufgaben, Methoden und bisherigen Ergebnisse. 2nd edition. Leipzig: C.H. Tauchnitz.
Gause, Georgii Frantsevich. 1932. Experimental studies on the struggle for existence. Journal of Experimental Biology 91: 389–402.
Haiman, John. 1983. Iconic and economic motivation. Language 591. 781–819.