Charlie Brown paperback books (Fawcett Publications): Nobody's Perfect (1969) and, as a bonus, Good Grief (1970). The size is 10.9 x 17.8 x 0.9cm. Originally, they were books with yellowish paper, but the whole thing has become brownish. There are no tears, but they feel old. The red cover is offered as a bonus because it's more heavily browned. I hope someone with interest will take a look.