Unveiling the super-orbital modulation of LSI +61 303 in X-rays
  We found evidence for the super-orbital modulation in the X-ray emission of LS I +61 303 from the longest monitoring date by the RXTE. The time evolution of the modulated fraction in the orbital light curves can be well fitted with a sinusoidal function having a super-orbital period of 1667 days. However, we have found a 281.8+/-44.6 day shift between the super-orbital variability found at radio frequencies and our X-ray data. We also find a super-orbital modulation in the maximum count rate of the orbital light curves, compatible with the former results, including the shift. 
Jian Li, Diego F. Torres, Shu Zhang, Daniela Hadasch, Nanda Rea, G.   Andrea Caliandro, Yupeng Chen, and Jianmin Wang
astro-ph.HE astro-ph.SR