13. 附录# 13.1. 数学符号 13.1.1. Mathematical symbols 13.1.2. Notations 13.1.3. Fractions and related constructions 13.1.4. Delimiter sizes 13.1.5. Text 13.1.6. Integrals and sums 13.1.7. Changing the size of elements in a formula 13.2. 术语表 13.3. Reference 13.3.1. 编辑工具 13.3.2. 参考内容