How was Odd Hassel awarded the Noble Prize?

Name: Odd Hassel. 
Country: Norwegian.
Date of Birth: 17 May 1897.
Date of Death: 11 May 1981.
The subject of Study: Conformation, conformational analysis, cyclohexane, organohalogen compound.
Noble Prize Year: Nobel Prize for Chemistry in 1969 for their work on Establishing conformational analysis.