Question: The 1974–75 Seattle SuperSonics season included which former Boston Celtics center as head coach?
Context: The 1972–73 Seattle SuperSonics season was the 8th season of the Seattle SuperSonics in the National Basketball Association (NBA).  The team finished the regular season in 6th place in the Western Conference with a 26–56 record, 21 wins behind the one obtained in their previous season.  Head coach Tom Nissalke was fired by the team in January after a 13–32 start and was replaced by his assistant Bucky Buckwalter. William Felton Russell (born February 12, 1934) is an American retired professional basketball player.  Russell played center for the Boston Celtics of the National Basketball Association (NBA) from 1956 to 1969.  A five-time NBA Most Valuable Player and a twelve-time All-Star, he was the centerpiece of the Celtics dynasty, winning eleven NBA championships during his thirteen-year career.  Russell holds the record for the most championships won by an athlete in a North American sports league (tied with Henri Richard of the National Hockey League).  Before his professional career, Russell led the University of San Francisco to two consecutive NCAA championships (1955, 1956), and he captained the gold-medal winning U.S. national basketball team at the 1956 Summer Olympics. The 1973–74 Seattle SuperSonics season was the 7th season of the Seattle SuperSonics in the National Basketball Association (NBA).  Following the resignation of Lenny Wilkens as a head coach after the 1971–72 season and a poor campaign in the 1972–73 season that saw the departure of general manager Bob Houbregs, the Sonics hired Boston Celtics' stalwart Bill Russell as head coach and general manager.  With Russell at the helm, the team finished in 6th place in the Western Conference with a 36–46 record.  The Sonics' home court, Seattle Center Coliseum, was the venue for the 1974 NBA All-Star Game. The 1986–87 Seattle SuperSonics season was the 20th season of the Seattle SuperSonics in the National Basketball Association.  Bernie Bickerstaff returned for his second season as head coach of the franchise and, despite little improvement over their previous season's 31–51 record, managed to clinch a spot in the playoffs and reach the Western Conference Finals, losing in four games to the Los Angeles Lakers. The 1988–89 Boston Celtics season was the 43rd season of the Boston Celtics in the National Basketball Association (NBA).  This was the first season for Jim Rodgers as head coach.  Rodgers had been a Celtics assistant coach prior to this season.  This year's Celtics team was severely hindered by the loss of star forward Larry Bird to a heel injury which required surgery.  Bird played only six early-season games before being lost to injury.  Initially, Bird was expected back in March, but it was delayed and ultimately became a season-ending injury.  The results were dramatic as the Celtics, who had averaged over 60 wins per season thus far in the 1980s, fell to just 42 wins in this season.  Coming into the season, the Celtics had been the Eastern Conference's #1 seed five years in a row.  This season they were the #8 seed, clinching a playoff spot in the season's final game.  This season included some bright spots, particularly the emergence of guard Reggie Lewis, who had been only a minimal bench contributor in his rookie season of 1987-88, but averaged nearly 20 points per game as a starter in 1988-89. The 1971–72 Seattle SuperSonics season was the 5th season of the Seattle SuperSonics in the National Basketball Association (NBA).  In their third season with Lenny Wilkens as head coach, the Sonics finished the regular season in sixth place in the Western Conference with a 47–35 record, their first winning record in franchise history.  Wilkens quit as head coach at the end of the season and was replaced by former Dallas Chaparrals coach Tom Nissalke. The 1974–75 Seattle SuperSonics season was the 8th season of the Seattle SuperSonics in the National Basketball Association (NBA).  In their second season with Bill Russell as head coach and with rookies comprising half the roster, the SuperSonics finished the regular season in 4th place in the Western Conference with a 43–39 record and reached the playoffs for the first time in franchise history.  After defeating the Detroit Pistons in 3 games in the first round in a best-of-three series, the team fell to the future champions Golden State Warriors in six games. The 1970–71 Seattle SuperSonics season was the Seattle SuperSonics 4th season in the National Basketball Association (NBA).  In their second season with Lenny Wilkens as head coach, the Sonics finished in 8th place in the Western Conference with a 38–44 record.  Trouble arose with the injury of top scorer Bob Rule, who tore his Achilles tendon three games into the season during a match against the Portland Trail Blazers and lost him for the remainder of the season. The 2007–08 Seattle SuperSonics season was the 41st season of the Seattle SuperSonics in the National Basketball Association (NBA) and the franchise's final season of play in Seattle before relocating to Oklahoma City to play as the Thunder.  With head coach P. J. Carlesimo as replacement of Bob Hill, who was fired at the end of the previous season, the SuperSonics finished in 15th place in the Western Conference with a franchise worst 20–62 record.  Seattle's first round draft pick and no. 2 overall Kevin Durant was chosen as the Rookie of the Year at the end of the season. The 1975–76 Seattle SuperSonics season was the 9th season of the Seattle SuperSonics in the National Basketball Association (NBA).  The SuperSonics finished the season in second place in the Western Conference with a 43–39 record, the same as the previous year and reached the playoffs for a second consecutive season, where they lost to the Phoenix Suns in the Conference Semifinals in six games.
Answer: William Felton Russell