说明：  非常好的分形集合入门级读物，包括引言、经典分形集合、自相似性和映射平面、度量空间、赋范空间、迭代函数系统等
(very good fractal set entry-level books, including the introduction and the classic fractal set, self-similarity and mapping plane, metric spaces, normed space, iterated function systems)