[1] CAD 二次开发 引用外部DWG并放到对应图层上
https://www.cnblogs.com/sguozeng/articles/4901589.html

[2] C# AutoCAD二次开发: 读取DWG文件将全部实体变为一个块。
https://blog.csdn.net/qq_41721686/article/details/100895546?spm=1035.2023.3001.6557&utm_medium=distribute.pc_relevant_bbs_down.none-task-blog-2_defaultOPENSEARCH_{default-2.nonecase&depth_1-utm_source=distribute.pc_relevant_bbs_down.none-task-blog-2}default_OPENSEARCHdefault-2.nonecase