Bibliografi : hlm. 235-237
No Inv.: 133419,133420/S/Perp/12/2c
Judul asli: "How it Work Series : Space Shuttles"
Bibliografi : hlm. 166-169
No Inv.: 3791-3800/P/Perp/98/10c
Bibliografi : hlm./ 343-344 No Inv.: 133958/SM/Perp/13/1c~136180/SM/Perp/13/1c~135867/SM/Perp/13/1c
Bibliografi : hlm. 444No Inv.: 142901-142905/P/Perp/14/5c
No Inv.: 5257-5259/S/Perp/86/3c~12813-12817/P/Perp/94/5c
Judul asli : "The Professional Secretary : Skill and Techniques for Recognition and Sources"