Question: What type of tennis do Mark Knowles and Andy Ram specialize in?

full_context: Document 1: Daniel Nestor: Daniel Mark Nestor {'1': ", '2': ", '3': ", '4': "} (Serbian Cyrillic: Данијел Несторовић; born September 4, 1972 as Danijel Nestorović) is a Canadian professional tennis player. He is one of the foremost doubles players in tennis history due to his longevity and continued success at the top of the men's game. s of 2016 , he is 11th for most men's ATP titles in Open Era history. In January 2016, Nestor became the first doubles player in ATP history to win 1000 matches.
Document 2: Raúl Ramírez: Raúl Ramírez (born 20 June 1953) is a retired Mexican professional tennis player. He was active during the 1970s and 1980s, and is regarded as one of the great all-around players of the modern era. Ramírez was also the first player to finish first in both singles and doubles Grand Prix point standings, accomplishing the feat in 1976. He attended and played tennis at the University of Southern California in Los Angeles.
Document 3: 2013 SAP Open – Doubles: Mark Knowles and Xavier Malisse were the defending champions but Knowles did not participate this year because of his retirement from professional tennis in September 2012.<br>
Document 4: 2009 Australian Open – Men's Doubles: Jonathan Erlich and Andy Ram were the defending champions, but Erlich chose not to participate due to an elbow injury, and only Ram competed that year.Ram partnered with Max Mirnyi, but lost to Feliciano López and Fernando Verdasco in the second round.
Document 5: 2008 French Open – Men's Doubles: Mark Knowles and Daniel Nestor were the defending champions, but did not compete together. Knowles partnered with Mahesh Bhupathi, but lost in the first round to Stephen Huss and Ross Hutchins.
Document 6: Mark Knowles: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis. He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor. At various times between 2002 and 2005 he was ranked World No. 1 in doubles. He is a five-time Olympian.
Document 7: David Sherwood: David Sherwood is a tennis coach and former British tennis player. In his only live Davis Cup match, Sherwood played doubles with Andy Murray beating the Israeli World No 4 doubles team of Jonathan Erlich and Andy Ram,
Document 8: Andy Roddick: Andrew Stephen Roddick (born August 30, 1982) is an American former professional tennis player from the US.
Document 9: 2002 RCA Championships – Doubles: Mark Knowles and Brian MacPhie were the defending champions but they competed with different partners that year, Knowles with Daniel Nestor and MacPhie with Nenad Zimonjić.
Document 10: 2008 Stella Artois Championships – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Knowles chose not to participate, and only Nestor competed that year.
Document 11: Bob Bryan: Robert Charles Bryan (born April 29, 1978) is an American male professional tennis player. He has won twenty-three Grand Slam titles: 16 in men's doubles and 7 in mixed doubles. He turned professional in 1998. With his twin brother Mike, he has been world No. 1 doubles player for much of the last several years, first achieving the top ranking in September 2003. The brothers were named ATP Team of the Decade for 2000–2009. The brothers became the second men's doubles team to complete the career golden slam at the 2012 Summer Olympics.
Document 12: Andy Ram: Andy Ram (Hebrew: אנדי רם‎ ‎ ; born April 10, 1980) is a retired Israeli professional tennis player. He is primarily a doubles player.
Document 13: 2009 BNP Paribas Open – Men's Doubles: Jonathan Erlich and Andy Ram were the defending champions, but Erlich chose not to participate due to injury, and only Ram competed that year.Ram partnered with Max Mirnyi, they lost in the final to Mardy Fish and Andy Roddick 6–3, 1–6, [12–14]
Document 14: Andre Agassi: Andre Kirk Agassi ( ; born April 29, 1970) is an American retired professional tennis player and former World No. 1 who was one of the sport's most dominant players from the early 1990s to the mid-2000s. Generally considered by critics and fellow players to be one of the greatest tennis players of all time, Agassi has been called the greatest service returner in the history of the game. Described by the BBC upon his retirement as "perhaps the biggest worldwide star in the sport's history", Agassi compiled performances that, along with his unorthodox apparel and attitude, saw him cited as one of the most charismatic players in history. As a result, he is credited for helping to revive the popularity of tennis during the 1990s.
Document 15: 2005 Mutua Madrileña Masters Madrid – Doubles: Mark Knowles and Daniel Nestor were the defending champions and successfully defended their title, defeating Leander Paes and Nenad Zimonjić 3–6, 6–3, 6–2 in the final. It was the 39th doubles title for Knowles and the 41th doubles title for Nestor, in their respective careers. It was also the 4th and final title of the year for the pair.
ground_truth: doubles