For german readers, an old but informative article: https://onlinelibrary.wiley.com/doi/abs/10.1002/ange.19891010104 https://onlinelibrary.wiley.com/doi/abs/10

For german readers, an old but informative article: https://onlinelibrary.wiley.com/doi/abs/10.1002/ange.19891010104 https://onlinelibrary.wiley.com/doi/abs/10.1002/ange.1989101...