Next to contribute were Weierstrass and Darboux but even when he made his contribution in 1914 Darboux wrote about the complexities of the general case:
Sa susunod na kontribusyon ay Weierstrass at Darboux ngunit kahit na kapag ginawa niya ang kanyang kontribusyon sa 1914 Darboux wrote tungkol sa complexities ng pangkalahatang mga kaso: