He explained the secondary rainbow through a similar analysis involving two refractions and two reflections. Other multiple reflections or refractions are more complex to predict but can be still useful. However, etendue is also conserved in refractions and reflections. It allowed among other things to protect from the sunlight's reflections and refractions. They squint by staring into the geometric refractions of light and record the results. Alhazen's problem can also be extended to multiple refractions from a spherical ball. Other factors include index of refractions for the three beams. In May 1968, "Refractions" and "Big Boss Man", were released in Japan and France, respectively.