Formal:
* Point of view
* Authorial stance
* Narrative voice
* Authorial intent
* Ideological framework
* Worldview
Informal:
* Angle
* Take
* Opinion
* Bias
* Prejudice (used when the perspective is negative or unfair)
* Outlook
* Vision
The best word to use will depend on the specific context and the level of formality you need.
For example, "point of view" is a general term that can be used in most cases. "Authorial stance" is a more formal term that emphasizes the author's position on the topic. "Narrative voice" is a more literary term that refers to the author's voice and how they present the story.
It's also important to consider the specific perspective you're trying to describe. For example, if the author is writing from a specific cultural background, you might use the term "cultural perspective."