Klay Alexander Thompson (born February 8, 1990) is an American professional basketball player for the Golden State Warriors of the National Basketball Association (NBA).
 The son of former NBA player Mychal Thompson, he played college basketball for three seasons at Washington State University, where he was a two-time first-team all-conference selection in the Pac-10.
 Thompson was selected in the first round of the 2011 NBA draft by Golden State with the 11th overall pick.
 In 2014, he and teammate Stephen Curry set a then NBA record with 484 combined three-pointers in a season, as the pair were given the nickname the "Splash Brothers".
 Thompson is a three-time NBA All-Star and a two-time All-NBA Third Team honoree.
 In 2015, he helped lead the Warriors to their first NBA Championship since 1975.
 Thompson helped the Warriors return to the NBA Finals for a third straight year in 2017, winning his second NBA Championship.
Juwan Antonio Howard (born February 7, 1973) is an American retired professional basketball player who currently serves as an assistant coach for the Miami Heat of the National Basketball Association (NBA).
 Howard formerly played for the Heat from 2010 until 2013.
 A one-time All-Star and one-time All-NBA power forward, he began his NBA career as the fifth overall pick in the 1994 NBA draft, selected by the Washington Bullets.
 Before he was drafted, he starred as an All-American on the Michigan Wolverines men's basketball team.
 At Michigan he was part of the Fab Five recruiting class of 1991 that reached the finals of the National Collegiate Athletic Association (NCAA) Men's Division I Basketball Championship in 1992 and 1993.
 Howard won his first NBA championship with Miami in the 2012 NBA Finals and his second NBA championship in the 2013 NBA Finals.
Daniel Richard "Danny" Green, Jr. (born June 22, 1987) is an American professional basketball player for the San Antonio Spurs of the National Basketball Association (NBA).
 He was a swingman from the University of North Carolina, where he played in more games (145) and had more wins (123) than any Tar Heel before him.
 Green is also the only player in the history of the Atlantic Coast Conference (ACC) with at least 1,000 points, 500 rebounds, 250 assists, 150 three-pointers, 150 blocks and 150 steals.
 He won an NCAA championship his senior year and was subsequently drafted by the Cleveland Cavaliers with the 46th overall pick in the 2009 NBA draft.
 During the 2013 NBA Finals, Green set an NBA record for most three-point field goals made in a Finals series.
 He then won an NBA championship with the San Antonio Spurs the following season, and became just the third player from UNC to win an NCAA championship and an NBA championship, the two others being James Worthy, and Michael Jordan.
 Known for his perimeter defense and three-point shooting, Green has been a key contributor on both ends on the floor throughout his NBA career, having been selected to his first NBA All-Defensive Second Team in the 2016-17 NBA season.
Draymond Jamal Green Sr. (born March 4, 1990) is an American professional basketball player for the Golden State Warriors of the National Basketball Association (NBA).
 Green, who plays primarily at the power forward position, was named to the NBA All-Defensive Team and won his first NBA Championship with the Warriors in 2015.
 Green was named an NBA All-Star and All-NBA Team member the following two seasons.
 In 2017, he won NBA Defensive Player of the Year and his second NBA Championship as a member of the Warriors.
Andre Tyler Iguodala ( ; born January 28, 1984) is an American professional basketball player for the Golden State Warriors of the National Basketball Association (NBA).
 The swingman was an NBA All-Star in 2012 and has been named to the NBA All-Defensive Team twice.
 Iguodala won an NBA championship with the Warriors in 2015, when he was named the NBA Finals Most Valuable Player.
 Iguodala helped the Warriors return to the NBA Finals for a third straight year in 2017, winning his second NBA Championship.
 He was also a member of the United States national team at the 2010 FIBA World Championship and 2012 Summer Olympics, winning the gold medal both times.
Alexander "Sasha" Olegovich Kaun (Russian: Александр Олегович Каун , born May 8, 1985) is a Russian former professional basketball player.
 He played college basketball in the United States for the University of Kansas for four seasons, where he won an NCAA championship in 2008 before being selected with the 56th overall pick by the Seattle SuperSonics in the 2008 NBA draft.
 He played seven seasons in Russia for CSKA Moscow.
 In 2015, he returned to the United States and played his only NBA season with the Cleveland Cavaliers, where he won an NBA championship in 2015–16.
 Kaun became one of the first Russians, along with Timofey Mozgov, in NBA history to win an NBA championship.
 He also represented Russia in the 2012 Summer Olympics.
Harrison Bryce Jordan Barnes (born May 30, 1992) is an American professional basketball player for the Dallas Mavericks of the National Basketball Association (NBA).
 He played college basketball for the North Carolina Tar Heels before being selected by the Golden State Warriors in the first round of the 2012 NBA draft with the seventh overall pick.
 Barnes won an NBA championship with the Warriors in 2015.
The 21 Irrefutable Laws of Leadership: Follow Them and People Will Follow You is a 1998 book written by John C. Maxwell and published by Thomas Nelson.
 It is one of several books by Maxwell on the subject of leadership.
 It is the book for which he is best-known.
 The book was listed on "The New York Times" Best Seller list in April 1999 after marketing company ResultSource manipulated the list by making it look like copies of "The 21 Irrefutable Laws of Leadership" had been purchased by thousands of individuals when, in actuality, ResultSource had simply made a bulk order of the book.
 The book had sold more than one million copies by 2015.
 Christian businessperson John Faulkner was inspired to found Christian business magazine "TwoTen" when he read "The 21 Irrefutable Laws of Leadership".
 Professional basketball player Harrison Barnes read and spoke positively of the book.
 Annie Grevers of "Swimming World Magazine" wrote of Maxwell's book, "it's cheesy, but ... it did me some good".
 Columnist Michael Hiltzik of the "Los Angeles Times" criticized Maxwell for including in the book "the insidious subtext ... that externalities have nothing to do with your failure", an assertion that Hiltzik argues research studies have demonstrated to be false.
Kareem Abdul-Jabbar (born Ferdinand Lewis Alcindor Jr.; April 16, 1947) is an American retired professional basketball player who played 20 seasons in the National Basketball Association (NBA) for the Milwaukee Bucks and the Los Angeles Lakers.
 During his career as a center, Abdul-Jabbar was a record six-time NBA Most Valuable Player (MVP), a record 19-time NBA All-Star, a 15-time All-NBA selection, and an 11-time NBA All-Defensive Team member.
 A member of six NBA championship teams as a player and two as an assistant coach, Abdul-Jabbar twice was voted NBA Finals MVP.
 In 1996, he was honored as one of the 50 Greatest Players in NBA History.
 NBA coach Pat Riley and players Isiah Thomas and Julius Erving have called him the greatest basketball player of all time.
John Calvin Maxwell (born 1947) is an American author, speaker, and pastor who has written many books, primarily focusing on leadership.
 Titles include "The 21 Irrefutable Laws of Leadership" and "The 21 Indispensable Qualities of a Leader".
 His books have sold millions of copies, with some on the New York Times Best Seller List.

Question: Which professional basketball player won a NBA championship and spoke positively on the book "the 21 irrefutable laws of leadership"?
Answer: Harrison Barnes