This page shows the different variations of the Jednostka organizacyjna 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.
It's four small squares, each sitting on the corner of one large square. The small squares are connected by the sides of the big square, giving it a connected look. Three of the four small squares are not shaded in and the only square that is shaded in is the small square on the bottom left hand corner.