May we suggest this interview with economist Sylvia Ann Hewlett on her findings that "sponsorship," "a type of strategic workplace partnership between those with potential and those with power," fosters more career gains than the classic mentorship.
 
http://www.washingtonpost.com/business/sylvia-ann-hewlitt-on-forgetting-mentorships-and-fostering-sponsorships-instead/2013/11/15/a9f86c8e-4b00-11e3-be6b-d3d28122e6d4_story.html