@misc{bas2000problems,
  title = {Problems in Hierarchical Production Planning Systems with Levels presenting different Horizon and Replanning Periods},
  author = {Ortiz Bas, Angel and Andrés Romano, Carlos and Vicens Salort, Eduardo and Alemany Díaz, María Del Mar},
  eventtitle = {1st World Conference on Productions and Operations Management (Sevilla, España. . 2000)},
  year = {2000}
}