![](https://media.springernature.com/w90/springer-static/cover/journal/10472/89/8.jpg?as=webp)
Volume 89, Issue 8-9
September 2021- Issue Editors:
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- Nikolaos F. Matsatsinis,
- Magdalene Marinaki,
- Yannis Marinakis,
- Panos M. Pardalos
9 articles in this issue