Finding subject-specific study materials for specific subtopics in the journals and publications for UPSC Mathematics Optional subject can be a challenging task. However, with the right approach and resources, it is possible to locate relevant materials. Here is a detailed explanation of how to find subject-specific study materials for specific subtopics in the journals and publications for UPSC Mathematics Optional subject:

1. Identify the subtopics:
Firstly, identify the specific subtopics within the UPSC Mathematics Optional subject that you are interested in studying. This will help to narrow down your search and focus on finding materials related to those subtopics.

2. Refer to UPSC syllabus:
Next, refer to the official syllabus provided by UPSC for the Mathematics Optional subject. The syllabus will provide a comprehensive list of topics and subtopics that are relevant for the exam. Use this as a guide to identify the specific subtopics you want to study.

3. Search for relevant journals and publications:
Once you have identified the subtopics, search for relevant journals and publications that cover those specific areas of study. Some popular journals and publications for UPSC Mathematics Optional subject include:
- Journal of the Indian Mathematical Society
- Journal of the Ramanujan Mathematical Society
- Mathematics Student
- Resonance - Journal of Science Education

4. Access online databases:
Many journals and publications have online databases that allow access to their articles and research papers. Some popular online databases for Mathematics include:
- JSTOR
- ScienceDirect
- SpringerLink
- IEEE Xplore

5. Utilize academic libraries:
Visit academic libraries, both physical and online, to access a wide range of books, journals, and research papers related to UPSC Mathematics Optional subject. Universities and educational institutions often have extensive collections that can be accessed by students.

6. Join online forums and platforms:
Join online forums and platforms dedicated to UPSC preparation, where aspirants and experts share study materials and resources. Platforms like EduRev provide a wide range of study materials, including journals and publications, specifically tailored for UPSC Mathematics Optional subject.

In conclusion, finding subject-specific study materials for specific subtopics in the journals and publications for UPSC Mathematics Optional subject requires a systematic approach. By identifying the subtopics, referring to the UPSC syllabus, searching for relevant journals and publications, accessing online databases, utilizing academic libraries, and joining online forums and platforms, you can gather a comprehensive collection of study materials for your preparation.