Krzysztof Diks, Andrzej Lingas, Andrzej Pelc. An Optimal Algorithm for Broadcasting Multiple Messages in Trees. In Danny Krizanc, Peter Widmayer, editors, SIROCCO 97, 4th International Colloquium on Structural Information & Communication Complexity, Monte Verita, Ascona, Switzerland, July 24-26, 1997. pages 69-80, Carleton Scientific, 1997.