Hannover have confirmed that new contracts have been agreed with Christian Schulz, Karim Haggui, Sofian Chahed and Markus Miller.
First-team midfielder Schulz and defender Haggui have signed extensions which will keep them at the awd-Arena until June 2014.
Regular substitute Chahed and back-up goalkeeper Miller have penned new contracts until the end of the 2012/2013 season.
Schulz told Hannover's official website: "I am happy to remain here. I feel it is best for me to commit myself to the club as the whole package at Hannover is excellent for me."
Schulz joined Hannover from Werder Bremen in June 2007, while Haggui arrived from Bayer Leverkusen at the start of the 2009/2010 season.
Chahed was a free transfer in 2009 after his deal at Hertha Berlin expired, while Miller was a summer signature in 2010 from second-tier Karlsruher.