This page shows the different variations of the Rachunek from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free. Icons are available in PNG and vector.
The Bill icon is primarily comprised of a rectangle that looks like a piece of computer paper, so the width is shorter than the length. Near the top is a straight horizontal line, which gives the impression of a title. In the bottom half of the rectangle are three horizontal lines, and each of these lines is broken to create a small space near the right end to make it look like you would see a description, space, price.