International Standard Book Number in 1965, has – 340 indicating the publisher, 01381 their serial number, and 8 being the check digit. This can be converted to ; the check digit does not need to be re-calculated. Since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with "Bookland" European Article Number EAN-13s. An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January
What Lies Below be left alone." Supervising producer Jeff Vlaming wrote "What Lies Below", his second episode of the season. Filmmaker Deran Sarafian served as the director, his first and only "Fringe" directional credit. The episode featured one-time guest appearances by actors Demore Barnes, Geoff Pierson, Conrad Coates, Natassia Malthe, and David Richmond-Peck. Actor Joshua Jackson, who plays an infected Peter Bishop in the episode, noted during shooting that he found inspiration from "imagin[ing] the worst hangover I've ever had and multiply it by ten". Actress Jasika Nicole was pleased that the writers decided to let her character discover Walter's secret, commenting "Astrid