Book sales to teens are booming – up by more than 25 percent since 1999, according to one industry analysis. Industry-watchers say fantasy and graphic novels, adventures, romances, humor and gritty coming-of-age tales are all selling in unprecedented quantities. Librarians say the quality and gravity of the content of books marketed to youth has increased as well, reflecting a more sophisticated teenage population. “Publishers are courting young adults in ways we haven’t seen since the 1940s,” said Michael Cart, a leading authority on young adult literature. “We are right smack-dab in the new golden age of young adult literature.” March 7, http://seattlepi.nwsource.com.