Alison M. Marr & W.D. Wallis 
Magic Graphs [PDF ebook] 

Magic squares are among the more popular mathematical recreations. Over the last 50 years, many generalizations of "magic" ideas have been applied to graphs. Recently there has been a resurgence of interest in "magic labelings" due to a number of results that have applications to the problem of decomposing graphs into trees. Key features of this second edition include:* a new chapter on magic labeling of directed graphs* applications of theorems from graph theory and interesting counting arguments* new research problems and exercises covering a range of difficulties* a fully updated bibliography and index This concise, self-contained exposition is unique in its focus on the theory of magic graphs/labelings. It may serve as a graduate or advanced undergraduate text for courses in mathematics or computer science, and as reference for the researcher.