51. | | Autor: Steyn, Hendrik C. | |
52. | | Autor: Ferreira, Sanette L. A. | |
53. | | Autor: Ferreira, Sanette L. A. Coautor: ; Harmse, Alet C. | |
54. | | Autor: Preston-Whyte, Robert | |
55. | | Autor: Ahmed, Zafar U. Coautor: ; Heller, Victor L. Hughes, Kevin A. | |
56. | | Autor: Ashley, Caroline Coautor: ; Jones, Brian | |
57. | | Autor: Felner, Ricardo Dias | |
58. | | Autor: Visser, Gustav | |