# Reference request: Federer-Besicovitch structure theorem


Theorem: Let $$E \subset \R^{N}$$ be a purely $$k$$-unrectifiable set such that $$E = \cup_{j=1}^\infty E_j$$ and $$\H^k(E_j)< +\infty$$. Then $$\H^k(\pi_{K}E) = 0$$ for $$\sigma$$-almost every $$k$$-plane $$K$$ in $$\R^N$$, where $$\sigma$$ denotes the uniform measure on $$O(N, k)$$.

Brian White proves the theorem by induction, assuming the case $$k = 1, N = 2$$. I am wondering if there is a place where I can read a proof of the theorem for this base case? I cannot find a self contained proof (assuming general familiarity with Hausdorff measure and rectifiability) anywhere.

Falconer provides an additional source (see comments below), but the language employed is slightly different. Wondering if there are any more recent expositions available.

Thanks!

The second page of Brian White's paper cites The Geometry of Fractal Sets by K. Falconer for a proof of Besicovitch's theorem (the $$k=1$$, $$N=2$$ case).