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| • | NAP - THE NATIONAL ACADEMIES PRESS | |
| • | NARCIS | |
| • | NATIONAL BIODIESEL BOARD | |
| • | NATIONAL SAFETY COUNCIL | |
| • | NATOTERM | |
| • | NBN - BUREAU VOOR NORMALISATIE/BUREAU DE NORMALISATION (BELGICA) | |
| • | NCBI - NATIONAL CENTER FOR BIOTECHNOLOGY INFORMATION | |
| • | NEMA - NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (ESTADOS UNIDOS) | |
| • | NEN - NEDERLANDS NORMALISATIE-INSTITUUT (PAISES BAJOS) | |
| • | NEW YORK PUBLIC LIBRARY | |
| • | NFPA - NATIONAL FIRE PROTECTION ASSOCIATION (ESTADOS UNIDOS) | |
| • | NIOSH - NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH (ESTADOS UNIDOS) | |
| • | NISO - NATIONAL INFORMATION STANDARDS ORGANIZATION (ESTADOS UNIDOS) | |
| • | NIST - NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY | |
| • | NIST - PHYSICAL REFERENCE DATA | |
| • | NIST CERAMICS WEBBOOK | |
| • | NIST CHEMISTRY WEBBOOK | |
| • | NIST DATA GATEWAY | |
| • | NIST DIGITAL LIBRARY OF MATHEMATICAL FUNCTIONS | |
| • | NIST HEAT TRANSMISSION PROPERTIES OF INSULATING AND BUILDING MATERIALS | |
| • | NIST PERIODIC TABLE OF THE ELEMENTS | |
| • | NIST REFERENCE ON CONSTANTS, UNITS AND UNCERTAINTY | |
| • | NIST SP 330. THE INTERNATIONAL SYSTEM OF UNITS (SI) 2019 EDITION | |
| • | NOBELPRIZE.ORG | |
| • | NORMATIVA LEGAL - GOBIERNO DE LA CIUDAD DE BUENOS AIRES | |
| • | NSAI - NATIONAL STANDARDS AUTHORITY OF IRELAND (IRLANDA) | |
| • | NSF - NORWEGIAN STANDARDS ASSOCIATION (NORUEGA) | |
| • | NSO - NATO STANDARDIZATION OFFICE (OTAN) | |
| • | NUEVO PARHADIGMA | |
| • | NUTRINFO | |
| • | NZS - SNZ STANDARDS NEW ZEALAND (NUEVA ZELANDA) | |
| A | B | C | D | E | F | G | H | I | J | K | L | M |
| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |