Many incidents and history on this subject. There is a very extensive online tutorial course from a Scandinavian outfit raising awareness in the pilot community for those airlines which purchase its content.
Facts and incidents speak louder than coursework.
It is impossible to ignore the many lives lost due to wings, designed to operate under a set of conditions, loosing lift capability due ice accumulation of some form or other.
Furthermore it is impossible to ignore the added weight by airframe icing on a large jet, which would not be taken into account in any performance calculations. (Imagine the weight of a few mm of airframe ice when you realise that the paint using standard 4-mil (0.1016-mm) paint thickness on a jumbo is already ~250kg!)
Fly safe, adhere to clean wing policies, or on certain models their black line philosophy, it's not worth loosing your life over a few liters of deicing fluid.