1 INTRODUCTION

2 DATA
2.1 Imaging
2.2 Spectroscopy

3 REDSHIFTS AND STELLAR MASSES
3.1 Photometric redshifts and stellar masses
3.2 Spectroscopic redshifts

4 GALAXY GROUP IDENTIFICATION
4.1 Method
4.2 Results

5 CONTRIBUTION OF LINE OF SIGHT AND ENVIRONMENT TO THE LENS STRUCTURE
5.1 Individual galaxies
5.2 Groups

6 VELOCITY-DISPERSIONS OF INDIVIDUAL GALAXIES

7 SUMMARY