 Complete the following phrase:   Sepp Zwicknagl, a pioneer of snow sports for disabled athletes, was a double-leg amputee Austrian skier who experimented skiing using prosthetics. His work helped pioneer technological advances for people with disabilities who wished to participate in winter sports. Advances were slow and it was not until 1974 that the first official world ski competition for physically impaired athletes, featuring downhill and a cross-country skiing, was held. The first Winter Paralympics were held in 