This article provides a brief introduction into typesetting LaTeX Matrix-like structures using AMS-LATEX packages....sum_{ \ substack{0 \ le i \ le m \\ 0 < j < n}} P(i, j) \\ 5 \...in \ Lambda \\ 7 0 \ le i \ le m \\ 8 0 < j < n 9 \ end{subarray}}...