[Here's a small reference I used in my «Sauces» folder in my cookbook manuscript:
Chef Karl Adam (d) in Germany is acknowledged as contributing the recipes in an old Asbach Uralt
wonderful small cookbook from the 1950's, dedicated to using the cognac in cooking, and HeddaAdlon, in the same cookbook, last owner of the famous Hotel Adlon in Berlin's «Unterden Linden,» is credited with saying: «Three indispensable ingredients are needed for the
creation of every good sauce, without any one of these the sauce will have neithersavour nor substance.»