Islington-based publisher Quarto said subdued trading continued in the third quarter, with some improvement in September.Revenue for the nine months to September 30 fell to $127.2m from $130.7m the year before. Pre-tax profit for the same period declined to $5.5m from £6m previously. The group said its trading performance in the nine months and 12 months to September 30th continues to be in line with expectations."Following the response to our products at the Frankfurt Book Fair in October, we noted that licensees and distributors around the world are largely adjusting to a world in which online retailing and digital books have challenged long-entrenched business models," Quarto said.2012 digital sales rose to 1.7% of total revenues at $2.225m compared to $1.455m in 2011. "In all English-language markets, traditional bookstore revenues are under pressure," it noted.CJ