What aspects of the first two progress reports can lead the reader to infer that “Flowers for Algernon” is written from the 1st person point of view?

It says stuff like 'I' and 'me'. It also has spelling mistakes that normally an author won't intentionally use when it's in 3rd person point of view. It had spelling errors because Charlie was still mentally disturbed when he wrote the first 2 progress reports and Daniel Keys (author) wanted to convey the message directly using this method. It also has a rather casual mood that in 3rd person point of view, it would be considered imformal and uncomplete. But because these reports are 1st person point of view, it adds a hint of detail into the overall story/"reports". Using all the text evidence from the book, the reader can infer that this book is written in a 1st person point of view.