511. | | Autor: Godfrey, Kerry B. | |
512. | | Autor: Getz, Donald Coautor: ; Anderson, Don Sheehan, Lorn | |
513. | | Autor: Gómez, César | |
514. | | Autor: Keller, Peter | |
515. | | Autor: Ampudia, Ricardo | |
516. | | Autor: Daoud, Danho | |
517. | | Autor: Manning, Edward W. | |
518. | | Autor: Marques, Armando Rocha | |
519. | | Autor: Najera, Margarita | |
520. | | Col.autor: OMT. Commission de l OMT pour l Europe | |