Publisher Bloomsbury said it remains cautious about current trading amid difficult retail conditions. The group also announced it has bought academic and professional publisher Continuum International Publishing for £20.1m as it beefs up its academic and professional division.Commenting on the acquisition Bloomsbury chief executive Nigel Newton said, "The acquisition is a transformational step in the delivery of a long held strategic objective to grow our academic publishing.""It is complementary to, and will substantially enhance, our Academic business, in particular giving it significantly more power in the US, helping to expand our increasing global market."The Harry Potter publisher said it expects the acquisition to produce cost synergies in excess of £1m in the first full year of combined operation.Meanwhile Bloomsbury, which recently launched Pottermore.com, will receive a share of the revenues from the sale of e-books from the site, starting later this year.Shares of Bloomsbury closed at 132p on Friday in London.CJ