Academic writing, business writing and such
There are courses on academic writing and on business writing. For people who already write correctly and well, these might be helpful. For people who lack sufficient control over the words and phrases of the English language, these courses are misleading.
There is only one kind of English prose -clear, concise and well constructed prose. If you control the words and phrases of the language it is easy to learn how to start with a “theme sentence” in every paragraph and the other little conventions of writing that are taught in these special writing courses. Without the vocabulary you do not have the resources to express yourself.
If your mind is muddled, no amount of courses on academic writing will help you.
That being said, once you have brought your vocabulary up to the required level, by all means read everything you can find on specialized writing. Start looking on the web where it is available free of charge. Or just buy a book on the subject.