1. The iron ore resources of the world : an inquiry made upon the initiative of the executive committee of the XI International Congress, Stockholm 1910;ANDERSSON Johan Gunnar,1910
2. Carta a Charles Kenneth Leith. Leith Papers, 7/13/12-4, Box 4;BALL Wilbur,1911
3. Carta a Charles Kenneth Leith. Leith Papers, 7/13/12-4, Box 4;BALL Wilbur,1911
4. Carta a Charles Kenneth Leith. Leith Papers, 7/13/12-4, Box 4;BALL Wilbur,1911
5. Carta a Charles Kenneth Leith. Leith Papers, 7/13/12-4, Box 4;BALL Wilbur,1911