Update README.md

README.md

@@ -16,7 +16,7 @@ The **Ontology of units of Measure (OM) 2.0** models concepts and relations that
 
 OM has a long history. In 2004, UnitDim, the precursor to OM, was published. In 2009, OM 1.0 followed, of which versions up to [1.8](http://www.wurvoc.org/vocabularies/om-1.8/) have been created. Finally, in 2017, OM 2.0 followed which is still maintained today. In the future we will move to OM 3.0.
 
-OM is based on several official paper standards, such as the [Guide for the Use of the International System of Units](http://physics.nist.gov/cuu/pdf/sp811.pdf), by the NIST – a document that represents the SI as established by the General Conference on Weights and Measures (CGPM) adapted to the United states, adapted back by us to the global standard (metre, litre, deca, tonne).
+OM is based on several official paper standards, such as the [Guide for the Use of the International System of Units](http://physics.nist.gov/cuu/pdf/sp811.pdf), by the NIST – a document that represents the SI as established by the General Conference on Weights and Measures (CGPM) adapted to the United States, adapted back by us to the global standard (metre, litre, deca, tonne).
 
 
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