You can find digital versions and supplementary materials on platforms like and the Internet Archive : English 900-Book 3 | PDF - Scribd
Historically, English 900 was sold with cassette tapes or vinyl records. Today, digital repositories often host the audio files (MP3s) that correspond to the lessons in the PDF. By downloading the Book 3 PDF and the accompanying audio, you can recreate the immersive classroom experience. You can read the sentence on the screen while listening to the native speaker pronunciation, bridging the gap between visual recognition and auditory comprehension. English 900 - Book 3 Pdf
To give you a taste of the difficulty, here are three authentic-style sentences from the middle of the course: You can find digital versions and supplementary materials