Gaya APA
      -Enz, J, F. ().
    Roi of human capital: measuring the economic value of employee performance .
    New York:
  Amacom.
  
Gaya MLA
      -Enz, Jac, Fitz.
    "Roi of human capital: measuring the economic value of employee performance".
    
    New York:
  Amacom,
  .
  Buku PPS Manajemen.