The University also graduated Nobel laureate, Paul D. Boyer.[226] Philo Farnsworth (inventor of the electronic television) received an honorary degree in 1967.[4] Harvey Fletcher (inventor of the hearing aid) is also a graduate of the university.[227][228] Four of BYU's thirteen presidents were alumni of the University. Additionally, alumni of BYU who have served as business leaders include Gary Crittenden ('76),[229][230] former Dell CEO Kevin Rollins ('84),[231] and Deseret Book CEO Sheri L. Dew.[232]