References

 
• Abramovitz, M., & Stegun, I. A. 1964, Handbook of Math. Functions (National Bureau of Standards, Wash. DC)  
• Adams, T. F. 1972, ApJ, 174, 439 NASA ADS  
• Ambartzumian, V. A. 1939. Theoretical Astrophysics (Gosteklizdat, Moscow)  
• Avrett, D., & Hummer, D. 1965, MNRAS, 130, 295 NASA ADS  
• Courant, R., & Hilbert, D. 1962, Methods of Mathematical Physics (Wiley-InterScience, New York), 1  
• Davidson, K., & Humphreys, R. M. 1997, ARA&A, 35, 1  
• Davidson, K. 1999, in $\eta$ Carinae at the Millenium, ed. J. A. Morse, R. M. Humphreys, & A. Damineli, ASP Conf. Ser., 179, 6  
• Frisch, H. 1980, A&A, 87, 357 NASA ADS  
• Hamann, F., Davidson, K., Ishibashi, K., & Gull, T. R. 1999, in $\eta$ Carinae at the Millenium, ASP Conf. Ser., 179, 116  
• Harrington, J. P. 1973, MNRAS, 162, 43 NASA ADS  
• Hummer, D. 1968, MNRAS, 138, 73 NASA ADS  
• Hummer, D. G., & Kunasz, P. B. 1980, ApJ, 236, 609 NASA ADS  
• Ivanov, V. V. 1973, Transfer of Radiation in Spectral Lines, NBS SP-285, US Dept. of Commerce (Washington, D. C.) (translated by Hummer, D. G. and Weppner, E.)  
• Johansson, S., Davidson, K., Ebbets, D., et al. 1996, in Science with Hubble Telescope-II, ed. P. Benvenuti, F. D. Macehetto, & F. J. Schreier, Space Telescope Institute, 361  
• Johansson, S., & Letokhov, V. S. 2001a, in $\eta$ Carinae and Other Mysterious Stars, ed. T. R. Gull, S. Johansson, & K. Davidson, ASP Conf. Ser., 242, 309  
• Johansson, S., & Letokhov, V. S. 2001b, A&A, 378, 266 NASA ADS  
• Johansson, S., & Zethson, T. 1999, in $\eta$ Carinae at the Millenium, ed. J. A. Morse, R. M. Humphreys, & A. Damineli, ASP Conf. Ser., 179, 171  
• Kalitkin, N. N. 1978, Numerical Methods (Russian) (Nauka Publ. House, Moscow)  
• Kurucz, R. L. 1988, Trans. IAOXXB, ed. M. NcNally (Kluwer, Dordrecht), 168  
• Mihalas, D. 1978, Stellar Atmospheres (W. H. Freeman and Company, New York)  
• Nahar, S. N., & Pradhan, A. K. 1994, J. Phys. B: At. Mol. Opt. Phys., 27, 429  
• Osterbrock, D. E. 1962, ApJ, 135, 195 NASA ADS  
• Sobolev, V. V. 1949a, AJ (Russia) 26, 129; (1954) 31, 231  
• Sobolev, V. V. 1949b, Astr. Zh., 26, 129; 1951. Astr. Zh., 28, 355; 1954. Astr. Zh., 31, 231; 1963. A Treatise on Radiative Transfer (translated from Russian) van Nostrand, Princeton, N.J.  
• Svelto, O. 1989, Principles of Lasers (Plenum Press, New York and London)  
• Weigelt, G., & Ebersberger, J. 1986, A&A, 169, 65