Slocum Websites:
navastro.fr
Navastro
Bienvenue dans la boutique en ligne de NavAstro. Spécialiste de toute la Navigation Astronomique : sextants, livres, calculatrices, stages de formation...
cigem.ca
Gemology World – Canadian Institute of Gemmology
Dedicated to research and advance in education in the field of gemmology. Gemlab Research & Technology. Gemological Books and Instruments. Professional Development.