The maritime bookshop Nautic Way offers a very wide choice of professional books, intended for the merchant navy, in particular from the IMO / IMO. Some of these books are mandatory on board ships.
OMI documents in digital version are only available in .pdf or .ebk depending on the works. The .ebk format can be used with the free IMO software (reader) which only works under Windows. We have no info on Mac, Linux or Android. The reader allows you to print digital books, and probably to make a .pdf to read it on Mac.