Public domain photos

The image shows an open book with a drawing of a circle on it. The book is placed on a flat surface and the drawing is accompanied by some text. The circle is composed of several smaller circles, each with a different color, and the text is written in a bold font.

The image shows an open book with a drawing of a circle on it. The book is placed on a flat surface and the drawing is accompanied by some text. The circle is composed of several smaller circles, each with a different color, and the text is written in a bold font.Open in library