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\bibitem{Liu_etal2006} {\textquotedblleft}\textit{Structure of multispecies charged particles in a quadratic trap}{\textquotedblright}. Liu YH, Chen ZY, Yu MY, Wang L, Bogaerts A, Physical review : E : statistical physics, plasmas, fluids, and related interdisciplinary topics \textbf{73}, 047402 (2006).   http://doi.org/10.1103/PhysRevE.73.047402

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