American pizza often has vegetable oil or shortening (often, but not always, olive oil) mixed into the dough; this is not as common in Italian recipes (for example, the pizza dough recipe in the influential Italian cookbook Il cucchiaio d'argento does not use oil). This can range from a small amount in relatively lean doughs, such as New York style, to a very large amount in some recipes for Chicago-style deep-dish dough. In addition, American pizza (at least thin-crust) is often made with a very high-gluten flour (often 13–14% protein content) of the type also used to make bagels; this type of flour allows the dough to be stretched rather thinly without tearing, similar to strudel or phyllo.