1 INTRODUCTION  
2 OBSERVATIONS  
3 STELLAR ATMOSPHERE MODELS  
4 METHODOLOGY  
5 RESULTS - PHOTOSPHERIC SURVEY  
6 RESULTS - INTERSTELLAR SURVEY  
7 DISCUSSION: RADIATIVE LEVITATION  
8 DISCUSSION: THE MASS-RADIUS RELATIONSHIP  
9 DISCUSSION: DISCREPANCIES IN WD0621-376  
10 DISCUSSION: INTERSTELLAR & CIRCUMSTELLAR ABSORPTION  
11 CONCLUSIONS