1. Ober Refraktion and Achsenlänge des menschlichen Auges;Strömberg;Acta Ophthalmol,1936
2. Ueber die menschliche Refraktionskurve;Betsch;Klin Monatsbl Augenheilkd,1929
3. A User's Guide to SAS-79,1979
4. Multiway Frequency Tables, The Log Linear Model;Brown,1979
5. US Bureau of the Census of Population: 1970: Vol 1, Characteristics of the population: Part 17,1973