Original: Zappalà, V.; M. di Martino and S. Cacciatori On the ambiguity of rotational periods of asteroids - The peculiar case of 52 Europa, Icarus, Vol.
Simplified: V. Zappalà, M. di Martino and S. Cacciatori On the ambiguity of rotational periods of asteroids - The peculiar case of 52 Europa, Icarus, Vol.