[1] https://link.springer.com/chapter/10.1007/978-3-642-29047-3_...
[2] https://www.sciencedirect.com/science/article/abs/pii/S09507...
[1] https://link.springer.com/chapter/10.1007/978-3-642-29047-3_...
[2] https://www.sciencedirect.com/science/article/abs/pii/S09507...