The Enneads of Plotinus are available in the Greek-English Loeb series.
Armstrong, A.H. (1967). The Architecture of the Intelligible Universe in the Philosophy of Plotinus. An Analytical and Historical Study. Amsterdam: Adolf M. Hakkert.
Blumenthal, H. J. (1971). Plotinus Psychology. His Doctrines of the Embodied Soul. The Hague: Martinus Nijhoff.
Dodds, E. R. (1960). Tradition and Personal Achievement in the Philosophy of Plotinus Journal of Roman Studies 50: 5-7.
Hadot, P. (1973). Plotin ou la simplicité du regard. Paris : Études Augustiniennes.
Hutchinson, D. M. (2018). Plotinus on Consciousness. Cambridge: Cambridge University Press.
Rist, J. M. (1967). Plotinus. The Road to Reality. Cambridge. Cambridge University Press.
Schürmann, R. (1983). Neoplatonic Henology as an Overcoming of Metaphysics Research in Phenomenology 13: 25–41.
Smith, A. (1978). Unconsciousness and Quasiconsciousness in Plotinus Phronesis 23 (3): 292–301.
Sweeney, L. (1961). Basic Principles in Plotinus’s Philosophy Gregorianum 42 (3): 506-16.
Warren, E. W. (1964). Consciousness in Plotinus Phronesis 9 (2): 83–97