What is the author's style in A Corner of the Universe by Ann M. Martin?

The book is written in first person from Hattie's perspective. The perspective is completely limited to Hattie's view. Hattie is eleven as the story opens. The reader has to keep in mind that Hattie's perspective is limited to the fact that she's a child. The reader doesn't know anything other than what is revealed to or by Hattie. For example, Hattie comes to realize that there's something in the family history impacting the actions of the adults. She says that it must have happened before her birth and could have happened much earlier than that. Hattie doesn't know what that something is and she doesn't ever figure that out. Another aspect of this limited perspective is that Hattie doesn't know why she wasn't told about Adam. She asks but doesn't get a satisfactory answer. She later wonders if her parents' fear that they might give birth to a child with Adam's challenges prevented them from having another child. She wants to ask this question but can't bring herself to say the words. These limitations to the perspective are important because they keep the reader focused on Hattie's perspective. The story is presented through dialogue and exposition. There is an appropriate amount of exposition and dialogue and both are reasonable to the story.