SIMBAD references

In this paper, the historic light curves of BL Lacertae in the infrared (JHK) bands have been constructed from the published literature. Maximum variations of ΔJ=2.29mag , ΔH=2.42mag , and ΔK=2.93mag and average color indices of J-H=0.78±0.11, H-K=0.78±0.12, and J-K=1.55±0.13 have been found. The relation between the color index and the brightness of the source and the correlation of color-color indices have been investigated. Our analysis shows that there is no clear correlation between the color index and the brightness, and the emission mechanism is non-thermal in the near-infrared.