Schödel, R. (2002). "A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way". Nature. Cilt 419 (6908 bas.). ss. 694-696. doi:10.1038/nature01121.
Doeleman, Sheperd S. (2008). "Event-horizon-scale structure in the supermassive black hole candidate at that Galactic Centre". Nature. Cilt 455 (7209 bas.). ss. 78-80. doi:10.1038/nature07245.
Reynolds, Christopher S. (2008). "Bringing black holes into focus". Nature. Cilt 455 (7209 bas.). s. 39. doi:10.1038/455039a.
