Biblioteca Digital de Teses e Dissertacoes (BDTD) - 28 February 1993 [Record Details] |
Johnson Space Center - 1 January 1993 [Record Details] |
Open Journal Systems Repositorio Español de Ciencia y Tecnología - 30 September 1993 [Record Details] |
SciELO - Cuba - 1 April 1993 [Record Details] |