(1.2.5.1) It is selected as a textbook of university lectures
Many universities publish syllabus (lecture information), and they include information about reference books. You should better to refer them. Especially, the classes for first grade targeting people who were high school students last year, so the books tend to be easy. They require less knowledge to read. However, excluding the case that the teacher is the same as the author himself/herself, the teacher-student relationship with the author or the colleague of the same university. If multiple universities choose the book, it is strong
signal for the quality.