I'm not aware of any credible academic work that refers to Nazism as "left wing".

Here's the problem with labeling the entire thing as "left wing" and being done with it: it tries to describe all policies by using one term, and it doesn't work.

While it is true that the Third Reich had some socialist leanings in economic policy, it doesn't appear that those policies were meant to outlast the war, and that does nothing to describe the (obviously) outlandishly authoritarian stances on social issues.

Economic policy and social policy need not be related. Being somewhat left wing on economics does not mean that one is liberal socially (see: Soviet Russia), but it also does not mean that one is authoritarian socially (see: almost no actual national government).