Gaya APA
      Heerkens.--, G, R, H, G, R. (2005).
    Project Management 24 lesson to help you master any project the employee handbook for enhancing corporate performance.-- .
    USA :
  McGrawHill.
  
Gaya MLA
      Heerkens.--, Gary, R., Heerkens.--, Gary, R..
    "Project Management 24 lesson to help you master any project the employee handbook for enhancing corporate performance.--".
    
    USA :
  McGrawHill,
  2005.
  Buku.