1. Acker, A., Marcout, J., Ochsenbein, F., Stenholm, B., & Tylenda, R. 1992, Garching: European Southern Observatory
2. Acker, A., Marcout, J., & Ochsenbein, F. 1996, First Supplement to the SECGPN, Observatoire de Strasbourg
3. A Method for Optimal Image Subtraction
4. Calibration of the MACHO Photometry Database