## 2 Literature Review
### Scientific Research on Sustainable Strategy Assessment
The analysis helps companies develop new recycling facilities or leverage existing ones, with an example illustrating the model implementation process. [PERSON] et al. [33] developed an integrated model to measure reverse logistics (RL) service quality for the company Komunalac Teslic, using the Delphi, FUCOM, and modified SERQUAL methods. The analysis showed that customer expectations were higher than the perceived quality, with statistical differences in 12 SQ statements. The company needed to improve its service to achieve satisfactory quality levels based on the findings from the questionnaire and statistical analysis. Also, in terms of logistics performance evaluation and MCDM application, [PERSON] et al. [34] reviewed over 120 studies (2010-2019), identifying common approaches and 13 potential research topics. The study suggests future opportunities within these trends, providing a comprehensive view of developments in the field. Research by [PERSON] et al. [35] proposed a two-stage approach to design a reverse logistics network for battery waste management, aiming to achieve economic and environmental goals. The first stage used SF-AHP to determine the weights of the objectives, with carbon emission reduction and employment maximization having the highest weights. The second stage applied MO-MILP to optimize the network in Turkey, with 100% satisfaction for employment and development goals, 96% for carbon emission reduction, and 75% for cost reduction. [PERSON] and [PERSON] [36] proposed a hybrid MCDM model using triangular fuzzy numbers (TFN) to select a third-party logistics (3 PL) provider for a food company in India. The model combines LOPCOW, FUCOM, and DOBI methods to evaluate and rank suppliers, helping to determine the optimal choice. The method was successfully tested, providing stable and reliable solutions for decision-making in the supply chain. Although many studies have applied MCDM methods to evaluate performance or select strategies, there are still significant limitations. First, the combination of MCDM methods is still limited, especially between fuzzy processing methods such as FAHP and NFAD. Second, the application of these methods in the context of sustainable logistics has not been fully studied, especially in developing countries such as Vietnam, where economic, social, and environmental factors have complex interactions and are heavily influenced by local policies and conditions. Based on the overview of the two literature streams above, it is possible to identify some important gaps that need to be researched. First, there is no integrated framework that uses FAHP and NFAD to evaluate and prioritize sustainable strategies in logistics, especially in the context of developing economies. Second, existing studies lack a multidimensional approach to comprehensively consider and analyze economic, social, and environmental factors in strategy assessment. Finally, existing assessment methods often have difficulty in providing objective and reliable weightings for sustainability factors, leading to limitations in the ability to make accurate and feasible decisions. This study aims to fill the above gaps by developing an integrated framework of FAHP and NFAD and by applying this framework to evaluate and select sustainable strategies in logistics in Vietnam. This is not only a theoretical contribution but also a practical one, helping businesses and policymakers build and implement sustainable strategies in a more effective and scientific way. Moreover,compared with the traditional AHP method and other sustainability decision models in the logistics industry. The FAHP-NFAD method excels in its ability to handle uncertainty and ambiguity in the evaluation process, where factors influencing strategic decisions are often not precisely determined. While AHP only uses definite values to compare criteria, FAHP applies fuzzy theory to reflect uncertainty, providing more accurate results in complex situations.