Sources

Every source backing a fact on vfridge limited's own page, deduplicated — the same source backing several facts appears once.

• https://link.springer.com/book/10.1007/3-540-45756-9 — https://link.springer.com/book/10.1007/3-540-45756-9
• https://link.springer.com/book/10.1007/b12029 — https://link.springer.com/book/10.1007/b12029