(Additional Note) I will remove this listing on the 20th due to studying for exams. Thank you for viewing. Denki Shoin d-BOOK Series Symmetrical Coordinate Method and Analysis of Unbalanced Three-Phase Circuits This is one of the reference books I purchased for the Class 1 Electrician exam. I bought it on Amazon a few years ago for about 10,000 yen. There are yellow highlighter marks on pages 5 and 6. I didn't see any other writing besides these two pages, but please forgive me if I missed anything. No pets, no smokers. Thank you.