Some readers have a backlight function. Unlike conventional screens that shine directly into our eyes, in e-ink diodes are located at the bottom or on the sides of the display and illuminate the "paper" itself. On the one hand, such illumination does not strain the eyes. On the other hand, the text in the corners is sometimes difficult to read, it seems to be blurred. Reading a book like
ITIL v4 foundation book on the reader without backlight will not work even at dusk, you will need an external light source. The price is not particularly affected by the presence of backlight.
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ITIL v4 foundation book https://www.best-services-now.info/sites/e-book.business/