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PHP File Open/Read/Close - W3Schools
PHP: readfile - Manual
How to Read a File in PHP Effectivelly - PHP Tutorial
Read a plain text file with php - Stack Overflow
How to Create, Write, Read, and Delete Files in PHP
Quick Tip: How To Read a Local File with PHP — SitePoint
PHP File Open: A Guide to Reading and Writing Files in PHP
6 Ways to Read Files In PHP - Into String, Array, And More!
How to Read and Write from Files in PHP - GeeksforGeeks
How to Read Text Files in PHP | Delft Stack