## 3 Methodology  
### Methodology Description  
This study evaluated and selected 15 sustainable strategies in the logistics sector in Vietnam, as shown in Table 1. Figure 2 illustrates the two-layer decision-making approach proposed by the study to evaluate these sustainable strategies. In the first layer, to identify the evaluation criteria for selecting sustainable strategies in the logistics industry, a group of experts in the field of logistics and sustainable development was assembled to discuss and develop evaluation criteria, ensuring the comprehensiveness and depth of the criteria. Then, the criteria were refined based on the literature review and expert opinions. The study then used FAHP to calculate the weight of each criterion based on expert assessment, thereby reflecting the relative importance of sustainability criteria in the logistics context. Next, NFAD was applied to determine the suitability of sustainable strategies based on their relationship with ideal and non-ideal values, thereby selecting the most potential strategies. Furthermore, to ensure the stability and reliability of the FAHP-NFAD model in selecting sustainable logistics strategies, a sensitivity analysis was performed to assess the change in results when there was a change in the weight of the criteria. Specifically, each weight of the main criteria was systematically adjusted to determine the influence of each criterion on the final ranking order of the options. Sensitivity analysis helped to verify the ability of the model to maintain consistency when faced with small fluctuations or significant changes in input factors. The combination of FAHP and NFAD ensured that the decision-making process could handle uncertainty and subjectivity in strategic assessment, creating a clear and adaptable analytical framework. Through calculations in these two layers, the study determined the overall score of each sustainable logistics strategy. These scores include both quantitative assessments and subjective language opinions of experts, reflecting the economic, social, and environmental aspects of the strategies in many dimensions. Choosing a sustainable strategy in logistics requires simultaneously considering many criteria of different importance. The combination of FAHP and NFAD helps to optimize the evaluation process, providing an analytical tool that is not only accurate and comprehensive but also flexible, responding well to the challenges in the current logistics context. FAHP facilitates the ranking of criteria by calculating weights based on expert opinions, thereby helping to clearly determine the priority of each factor in the assessment. NFAD then supports the evaluation of options based on these key criteria to create optimal, fair, and balanced results between conflicting factors. The FAHP-NFAD approach not only helps to evaluate sustainability strategies scientifically but also plays an important role in guiding strategic decisions on sustainable logistics development in Vietnam. In this study, the Triple Bottom Line approach served as the foundation for analyzing and evaluating 15 sustainable logistics strategies in Vietnam. The combination of the FAHP and NFAD methods helped establish a systematic and quantitative evaluation process, supporting the consideration of three economic, social, and environmental factors. Previous studies have mainly focused on each individual aspect of sustainability without a comprehensive synthesis method that fully reflects the complex relationships between these factors. This study overcomes this limitation by applying a multi-criteria decision-making model, consistent with the Triple Bottom Line theory, thereby providing a comprehensive