International ISBN Agency (Ed.). Publishers International ISBN Directory 2012. Berlin, Boston: De Gruyter Saur, 2011. Web. Retrieved 23 May. 2013, from http://www.degruyter.com/view/product/178351

International ISBN Agency (Ed.) (2011). Publishers International ISBN Directory 2012. Berlin, Boston: De Gruyter Saur. Retrieved 23 May. 2013, from http://www.degruyter.com/view/product/178351

International ISBN Agency (Ed.). 2011. Publishers International ISBN Directory 2012. Berlin, Boston: De Gruyter Saur. Retrieved 23 May. 2013, from http://www.degruyter.com/view/product/178351