PSX Extreme - Preview, by Arnold Katayev: "The biggest addition to Sigma will be Rachel as a full-fledged playable character. Team Ninja emphasizes that a lot of the new content found in Sigma will be when you're playing Rachel's segments." - http://www.psxextreme.com/ps3-previews/59.html
1UP - News, previews, images, videos, and links. - http://www.1up.com/do/gameOverview?cId=3153721
GameSpot - News, previews, images, videos, links, and a forum. - http://www.gamespot.com/ps3/action/ninjagaidensigma/
GameStats - Videos, screenshots, article links, and a message board. - http://www.gamestats.com/objects/856/856529/
IGN - Screenshots, videos, previews, news, and a message board. - http://ps3.ign.com/objects/856/856529.html
GameSpy - Preview, news, and screenshots. - http://ps3.gamespy.com/playstation-3/ninja-gaiden-sigma/