A course book is an essential resource that helps students to acquire knowledge, understand concepts and enhance their learning experience. However, when it comes to academic writing, it's important to use a range of synonyms instead of just repeating the phrase "course book" over and over again. Words like textbook, primer, manual, handbook, guidebook, and workbook can be used interchangeably with "course book" to add variety and depth to your writing. Furthermore, the context of your piece and the target audience should guide your selection of synonyms. So, next time you're writing an essay or academic paper, consider using some of these synonyms for "course book" to make your writing more engaging and varied.