• https://repository.uneca.org/handle/10855/43845
• https://repository.uneca.org/handle/10855/43848
• https://repository.uneca.org/handle/10855/43862
• https://repository.uneca.org/handle/10855/43874
• https://repository.uneca.org/handle/10855/43873
• https://repository.uneca.org/handle/10855/43875