1. Introduction

2. Definition and Background  
2.1. Task Definition  
2.2. Structure of CRS

3. Ontology and Existing Surveys

4. Main Approaches & Discussion  
4.1. Language Models  
4.2. External Knowledge  
4.3. External Guidance

5. Datasets  
5.1. Statistical Analysis  
5.2. Limitations

6. Evaluation Methods  
6.1. Recommendation Evaluation  
6.2. Language Evaluation

7. Challenges & Future Trends

8. Conclusion