DOS doesn't seem to have 32-bit, maybe I just don't know
If you're just talking about protected mode, I recommend Teacher Zhou Mingde's books:
"80386 and Its Programming in Protected Mode" Tsinghua University Press, gives a detailed introduction to the 80386 protection mechanism and multitasking mechanism
"80386 Under the UNIX Environment" Tsinghua University Press, talks about how the system is initialized, how to switch from real mode to protected mode, and how to implement virtual 8086 mode. Current systems are probably more or less the same
If you want even more detail, the most comprehensive thing is to read Intel's CPU manuals and developer guides. There are ones for each CPU, and they're easy enough to find online, but they're all in English. For Chinese, only bookstores have them.