Keywords: recombination lines — stars: formation — ISM: molecules — radio lines: ISM

1. INTRODUCTION

2. OBSERVATIONS AND DATA REDUCTION

2.1. Source Selection

2.2. Observation & Data Reduction

3. RESULT

3.1. RRL Detections

3.2. Other Sources

4. DISCUSSION

4.1. Distance and Galactocentric Distance Distributions

4.2. RRL and Maser Line Intensity Distributions

4.3. Line Width Distribution

5. SUMMARY