1,2,4,8 과 1,3,7

Parallelizability of spheres

 

 

• Cross Products of Vectors in Higher Dimensional Euclidean Spaces
  
  • W. S. Massey
  • The American Mathematical Monthly, Vol. 90, No. 10 (Dec., 1983), pp. 697-701    
     
    

• The Scarcity of Cross Products on Euclidean Spaces
  
  • Bertram Walsh
  • The American Mathematical Monthly, Vol. 74, No. 2 (Feb., 1967), pp. 188-194