1. 1992 National Ambulatory Medical Care Survey Data File Documentation,1994
2. 1993 National Ambulatory Medical Care Survey Data File Documentation,1996
3. 1994 National Ambulatory Medical Care Survey Data File Documentation,1997
4. 1995 National Ambulatory Medical Care Survey Data File Documentation,1997
5. 1996 National Ambulatory Medical Care Survey Data File Documentation,1998