Instrukcja obsługi and other 86,700 icons from Icons8 icon pack follow the visual guidelines of the operating systems: Windows, iOS, Android KitKat, and Material. PNG format is free up to 100x100 px. Icons are availble for download in PNG and vector (SVG, PDF, EPS, and more).
This icon for User Manual looks like an open book. The cover of the book looks like a rectangle with rounded edges, and two pages are visible, separated by a line in the middle of the pages. On the page on the right, there is a large lower case letter i.