Gaya APA
      Huggins, R., Izushi, H. (2011).
    Competition,competitive advantage and clusters : The ideas of micheal porter .
    New York:
  oxford university press.
  
Gaya MLA
      Huggins, Robert., Izushi, Hiro.
    "Competition,competitive advantage and clusters : The ideas of micheal porter".
    
    New York:
  oxford university press,
  2011.
  UMUM.