SIMBAD references

New differential time-series observations of BL Camelopardalis were secured using B and V filters. It was confirmed that BL Cam is an optical double star. Differential magnitudes were obtained through a photometric profile reduction procedure to eliminate the influence of a faint adjacent star. Variations in O-C values for light maxima were investigated. We found that the parabolic period variation was recently reversed. The periods of BL Cam were investigated, and five frequencies were determined using Fourier analysis. We also investigated the relationship between metallicities and period ratios, and we compared the theoretical and observational relationships. It was found that the theoretical relationship is better than the observational one for BL Cam.