         )
     }
 
+    /**
+     Returns US teaspoon `[US tsp]` volume unit.
+     
+     - author: Michal Konturek
+     */
     public static var us_teaspoon: VolumeUnit {
         return VolumeUnit(
             name: "US teaspoon",
-            symbol: "tsp",
+            symbol: "US tsp",
             ratio: NSDecimalNumber(mantissa: 492892159375, exponent: -14, isNegative: false)
         )
     }
 
+    /**
+     Returns US fluidram `[US fl dr]` volume unit.
+     
+     - author: Michal Konturek
+     */
     public static var us_fluidram: VolumeUnit {
         return VolumeUnit(
             name: "US fluidram",


extension NSNumber {

    public func us_hogshead() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_hogshead)
    }

    public func us_barrel() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_barrel)
    }

    public func us_gallon() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_gallon)
    }

    public func us_quart() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_quart)
    }

    public func us_pint() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_pint)
    }

    public func us_cup() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_cup)
    }

    public func us_gill() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_gill)
    }

    public func us_fluidounce() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_fluidounce)
    }

    public func us_tablespoon() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_tablespoon)
    }

    public func us_teaspoon() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_teaspoon)
    }

    public func us_fluidram() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_fluidram)
    }

    public func us_minim() -> Quantity {
        return Quantity(amount: self, unit: VolumeUnit.us_minim)
    }

        )
    }

    /**
     Returns US cup `[US cp]` volume unit.
     
     - author: Michal Konturek
     */
    public static var us_cup: VolumeUnit {
        return VolumeUnit(
            name: "US cup",
