1. Rotors in polygons and polyhedra;Goldberg;Math. Comp.,1960
2. Rotors within rotors;Goldberg;Am. math. Mon.,1954
3. N-gon rotors making n+1 contacts with fixed simple curves;Goldberg;Am. math. Mon.,1962
4. N-gon rotors making n+1 contacts with fixed simple curves;Goldberg;Am. math. Mon.,1964
5. Über die innen-drehbare Kurve eines Vieleckes;Fujiwara;Tôhoku Sci. Rep.,1919