From 1952 to 1980 Jacques Lacan gave an annual seminar in Paris. The books of the seminars are edited by Jacques-Alain Miller.
For a complete list of the seminars see: SEMINARS OF JACQUES LACAN – CONTENTS
The original French texts of the seminars online: STAFERLA
Many of Lacan’s seminars in English translation by Cormac Gallagher can be downloaded in PDF form: Seminars « Lacan in Ireland
Lacan, J. (2006). Écrits. The First Complete Edition in English (trans.) B. Fink. New York, London: W.W. Norton.
It can be downloaded in PDF form: JL_0393329259.pdf
Krutzen, H. (2009). Jacques Lacan Séminaire 1952-1980. Index référentiel. Paris: Economica.
This lists references in the seminars to themes and proper names.
Evans, D. (1996). An Introductory Dictionary of Lacanian Psychoanalysis. London & New York: Routledge.
Lang, H. (1977). Language and the Unconscious. Lacan’s Hermeneutics of Psychoanalysis (trans) T. Brockelman. New Jersey: Humanities Press.
First published in German in 1973 this was written by one Hans-Georg Gadamer’s doctoral students and served as the first introduction of Lacan’s thought in German.
Roudinesco, E. (1997). Jacques Lacan (trans) B. Bray. New York : Columbia University Press.
This intellectual biography usefully sets the development of Lacan’s thought into its historical context.
Benvenuto, B. and Kennedy, R. (1986). The Works of Jacques Lacan. An Introduction. London: Free Association Books.
This remains a good introduction to Lacan’s work written in plain English.
Benvenuto, S. (2020). Conversations with Lacan. Seven Lectures for Understanding Lacan. London & New York: Routledge.
This is by far the best of the more recent introductions to Lacan’s thought by an eminent psychoanalyst and former student of Lacan.