Boston Celtics president Brad Stevens has received permission from teams to interview several assistant coaches for his franchise's head coaching job, including the LA Clippers' Chauncey Billups, sources told ESPN.

Stevens started making calls on Wednesday to get the OK to talk to several candidates, including Billups, Milwaukee Bucks' Darvin Ham and Charles Lee, Dallas Mavericks' Jamahl Mosley and Brooklyn Nets' Ime Udoka, sources told ESPN.

The Celtics' list is expansive beyond these candidates, who comprise a group of assistants who've all been interviewed for other head coaching openings in recent years.

Stevens stepped down as Celtics coach to replace Danny Ainge running the Celtics' front office and spent the first several days of his coaching search interviewing members of his former coaching staff, including Jay Larranaga, Jerome Allen, Scott Morrison and Joe Mazzulla, sources said.

Along with the Indiana Pacers, Orlando Magic and Portland Trail Blazers, Boston is one four teams with head coaching openings.