Introduction:
The UPSC Law Optional subject is a highly competitive and challenging subject that requires extensive knowledge and understanding of various legal concepts and principles. In order to excel in this subject, it is important to refer to multiple sources to broaden one's knowledge base and gain a comprehensive understanding of the subject matter.

Importance of Referring to Multiple Sources:
1. Depth of knowledge: Referring to multiple sources allows candidates to delve deep into the subject and gain a thorough understanding of different legal concepts. It helps in developing a comprehensive knowledge base, which is crucial for answering questions in the UPSC Law Optional paper.

2. Breadth of coverage: Law is a vast subject with numerous sub-topics and areas of specialization. Referring to multiple sources helps in covering a wide range of topics and ensures that candidates have a holistic understanding of the subject. It helps in addressing questions from various dimensions and perspectives.

3. Exposure to different viewpoints: Law is not a static subject and is subject to interpretation and changes over time. Referring to multiple sources provides candidates with exposure to different viewpoints, interpretations, and case laws. It helps in developing a critical and analytical approach towards legal issues and enhances the quality of answers in the exam.

4. Enhanced answer writing skills: UPSC Law Optional paper requires candidates to present their answers in a clear, concise, and well-structured manner. Referring to multiple sources helps in improving answer writing skills by providing candidates with different perspectives, arguments, and examples that can be incorporated into their answers. It helps in presenting a well-rounded and comprehensive response to the questions asked.

5. Current updates: Law is a dynamic field that undergoes changes and developments regularly. Referring to multiple sources helps in staying updated with the latest legal developments, amendments, and case laws. It ensures that candidates have accurate and up-to-date information while answering questions in the exam.

Conclusion:
In conclusion, referring to multiple sources is highly recommended for the UPSC Law Optional subject. It helps in developing a comprehensive understanding of the subject, covering a wide range of topics, and enhancing answer writing skills. By referring to multiple sources, candidates can broaden their knowledge base, gain exposure to different viewpoints, and stay updated with the latest legal developments. It ultimately improves their chances of performing well in the UPSC Law Optional paper.