★ This is a boxed set of 5 books: "Mathematical Formulation of Problems," "Basic Mathematics (I)," "Sampling Inspection," "Marketing Research," and "Cybernetics." ★ These are old books, nearly 70 years old, but please consider them if you are interested. ◉ A5 size. Boxed. Published by Misuzu Shobo on November 25, 1957. Original price: ¥450 ◉ The main body is paperback. ◉ The box has scratches, yellowing, noticeable stains and dirt overall, and damage to the corners, indicating significant wear and tear typical of old books. ◉ Includes a monthly report, but it shows signs of use such as yellowing, creases, wrinkles, and stains on the edges. ◆ "Mathematical Formulation of Problems": 55 pages. Images 11 are the table of contents. ⚫︎ The cover has scratches, stains, dirt, some creases, and slight yellowing and stains on the edges, and some pages have underlining (see image 12), and stains on pages 14 and 15 (image 13), but there are no problems with reading. ◆ "Basic Mathematics": 121 pages. Images 14-16 are the table of contents. ⚫︎ The cover has scratches, stains, dirt, and slight yellowing and stains on the edges, and a folded corner on the bottom corner of the last page, but there is no underlining in the text. ◆ "Sampling Inspection": 110 pages. Images 17 and 18 are the table of contents. ⚫︎ The cover has scratches, stains, dirt, and yellowing and stains on the edges, but there is no underlining in the text. ◆ "Marketing Research": 56 pages. Image 19 is the table of contents. ⚫︎ The cover has scratches, stains, dirt, and yellowing and stains on the edges, yellowing and stains on the title page and the last page, and a vertical line drawn in red pencil on page 36 (no image), but there are no problems with reading. ◆ "Cybernetics": 26 pages. The last image is the table of contents. ⚫︎ The cover has scratches, stains, dirt, yellowing on the edges, damage to the upper corners, and yellowing and stains on the edges, yellowing and some stains on the title page and the endpaper, and underlining in red pencil on some pages (no image), but there are no problems with reading.