Παραπομπή σε μορφή APA (7η εκδ.)

Guthke, K. S. Are we alone?: The idea of extraterrestrial intelligence in philosophy and literature from Copernicus to H.G. Wells / Karl S. Guthke. Utopian vision, technological innovation and poetic imagination.(1990).

Παραπομπή σε μορφή Chicago (17η εκδ.)

Guthke, Karl S. "Are We Alone?: The Idea of Extraterrestrial Intelligence in Philosophy and Literature from Copernicus to H.G. Wells / Karl S. Guthke." Utopian Vision, Technological Innovation and Poetic Imagination.(1990) .

Παραπομπή σε μορφή MLA (8th εκδ.)

Guthke, Karl S. "Are We Alone?: The Idea of Extraterrestrial Intelligence in Philosophy and Literature from Copernicus to H.G. Wells / Karl S. Guthke." Utopian Vision, Technological Innovation and Poetic Imagination.(1990), .