Writing FreeDOS Programs in C (2020)
On the other hand,
"PC intern system programming : the encyclopedia of DOS programming know how" - 1992
https://archive.org/details/pcinternsystempr0000tisc
With examples in C, C++, Turbo Pascal, QuickBasic, MASM and TASM.
Watcom is arguably the best C/C++ developer’s toolbox for DOS. It includes a 32-bit extender, so your programs are no longer limited to the standard < 1MB of RAM while being able to take advantage of what essentially is bare metal programming.