FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH. "Ru." The Oxford Dictionary of Abbreviations. Oxford University Press. 1998. Encyclopedia.com. 9 Jul. 2009 <http://www.encyclopedia.com>.
FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH. "Ru." The Oxford Dictionary of Abbreviations. Oxford University Press. 1998. Encyclopedia.com. (July 9, 2009). http://www.encyclopedia.com/doc/1O25-Ru.html
FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH. "Ru." The Oxford Dictionary of Abbreviations. Oxford University Press. 1998. Retrieved July 09, 2009 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O25-Ru.html