Morgan, Lewis H. Systems of consanguinity and affinity of the human family. Smithsonian Contributions to Knowledge 17. Washington, 1871.
A data dump in the truest sense of the word—and I do use it affectionately—Morgan’s big book is the rock upon which the scientific study of kinship is built. Systems was reprinted in 1997 by the University of Nebraska Press, with an Introduction by Elisabeth Tooker.
Lévi-Strauss, Claude. The elementary structures of kinship. Translated from the French by James Harle Bell, John Richard Von Sturmer, and Rodney Needham, editor. Boston: Beacon Press, 1969.
To the best of my knowledge, the chronology of this work is as follows: In 1948 Lévi-Strauss presented Les structures élémentaires de la parenté as his doctoral thesis at the Sorbonne. (The manuscript, incidentally, now resides at the Henry Ransom Center at UT-Austin.) The following year an English translation was published as The elementary structures of kinship, though I am unclear as to the bibliographic data. In 1967 a second edition of Les structures élémentaires de la parenté was published by Mouton. The above translation of Elementary structures is, if I understand correctly, of that 1967 edition.
Hrdy, Sarah Blaffer. Mothers and others: the evolutionary origins of mutual understanding. Cambridge, Mass.: Belknap Press of Harvard University Press, 2009.
This wonderful book should thoroughly disabuse any reader of the notion that the nuclear family is the natural state of affairs. There is a good interview with the author in the form of a two part blog post here and here.
Godelier, Maurice. The metamorphoses of kinship. Translated by Nora Scott. London; New York: Verso, 2011.
This is a translation of Godelier’s 2004 French original which Jack Goody described as “a blockbuster of a book.”