Leedy, Paul D. Practical research : planning and design. - 8th ed. / Paul D. Leedy and Jeanne Ellis Ormrod. - Upper Saddle River, N.J. : Prentice Hall, c2005. - xxiii, 319 p. : ill. ; 28 cm. Includes bibliographical references (p. 309-311) and index. eng. ISBN: 0131108956 TZS 69560.12 Subjects--Topical Terms: Research Dewey Class. No.: 300.72 LEE