The book "Three Hearts and Three Lions" by Poul Anderson strongly influenced "Dungeons & Dragons", having a dwarf named Hugi with a Scottish accent. Most popular portrayals of dwarves feature such an accent. Dwarves tend to be more useful for combat-oriented players, as they gain a number of special abilities and bonuses in combat, mostly related to their hardiness and smaller stature compared to humans. Dwarves are also resistant to poison and magic, can see in the dark (a skill called "infravision" in earlier editions and "darkvision" beginning with third edition), and can detect different types of mining-related features underground, such as sloping tunnels. The dwarven ability to detect a sloping passage underground is also taken directly from Anderson's book.