diff --git a/source/AbstractPhysicalQuantity.php b/source/AbstractPhysicalQuantity.php
index 0d61bbf..607ef28 100644
--- a/source/AbstractPhysicalQuantity.php
+++ b/source/AbstractPhysicalQuantity.php
@@ -211,6 +211,30 @@ public function isEquivalentQuantity(PhysicalQuantityInterface $testQuantity)
         return get_class($this) === get_class($testQuantity);
     }
 
+    /**
+     * @see \PhpUnitsOfMeasure\PhysicalQuantityInterface::isUnitDefined
+     */
+    public static function isUnitDefined($name) {
+    	$units = static::getUnitDefinitions();
+    	foreach ($units as $unit) {
+    		if ($name === $unit->getName() || $unit->isAliasOf($name)) {
+    			return true;
+    		}
+    	}
+    	return false;
+    }
+    
+    /**
+     * @see \PhpUnitsOfMeasure\PhysicalQuantityInterface::listAllUnits
+     */
+    public static function listAllUnits() {
+    	$return = array();
+    	$units = static::getUnitDefinitions();
+    	foreach ($units as $unit) {
+    		$return[$unit->getName()] = $unit->getAliases();
+    	}
+    	return $return;
+    }
 
     /**
      * Get the unit definition array
diff --git a/source/PhysicalQuantityInterface.php b/source/PhysicalQuantityInterface.php
index 63a804b..2cdb671 100644
--- a/source/PhysicalQuantityInterface.php
+++ b/source/PhysicalQuantityInterface.php
@@ -71,4 +71,21 @@ public function subtract(PhysicalQuantityInterface $quantity);
      * @return boolean True if the quantities are the same, false if not.
      */
     public function isEquivalentQuantity(PhysicalQuantityInterface $testQuantity);
+    
+    /**
+     * Verify if the given value respond to an already defined unit of meaure of the current
+     * phisical quantity.
+     * 
+     * @param string $name the string to verify
+     * 
+     * @return boolean True if $name has been defined into the current physical quantity, false if not.
+     */
+    public static function isUnitDefined($name);
+    
+    /**
+     * Return a list of all the unit of measure defined in the current physical quantity
+     * 
+     * @return array of all units as strings.
+     */
+    public static function listAllUnits();
 }
diff --git a/tests/AbstractPhysicalQuantityTest.php b/tests/AbstractPhysicalQuantityTest.php
index 19ce3f2..bed713f 100644
--- a/tests/AbstractPhysicalQuantityTest.php
+++ b/tests/AbstractPhysicalQuantityTest.php
@@ -5,6 +5,7 @@
 use PHPUnit_Framework_TestCase;
 use PhpUnitsOfMeasure\AbstractPhysicalQuantity;
 use PhpUnitsOfMeasure\UnitOfMeasureInterface;
+use PhpUnitsOfMeasure\UnitOfMeasure; // can be removed after #63 is closed
 use PhpUnitsOfMeasure\Exception\PhysicalQuantityMismatch;
 use PhpUnitsOfMeasure\Exception\DuplicateUnitNameOrAlias;
 use PhpUnitsOfMeasure\Exception\NonNumericValue;
@@ -33,6 +34,28 @@ protected function getTestUnitOfMeasure($name, $aliases = [])
 
         return $newUnit;
     }
+    
+    /**
+     *  This function is a workaround introduced for #63, waiting for a most suitable solution.
+     *  When #63 is closed, this method can be removed, and any call to its should be
+     *  replaced with calls to the original $this->getTestUnitOfMeasure(...)
+     */
+    protected function getTestUnitOfMeasureSafe($name, $aliases = [])
+    {
+    	$newUnit = new UnitOfMeasure(
+    			$name,
+    			function ($valueInNativeUnit) {
+    				return $valueInNativeUnit / 1;
+    			},
+    			function ($valueInThisUnit) {
+    				return $valueInThisUnit * 1;
+    			}
+    			);
+    	foreach ($aliases as $alias) {
+    		$newUnit->addAlias($alias);
+    	}
+    	return $newUnit;
+    }
 
     /**
      * @covers \PhpUnitsOfMeasure\AbstractPhysicalQuantity::addUnit
@@ -217,6 +240,52 @@ public function testGetAllUnits()
         $this->assertEquals($array, $expected);
     }
 
+    /**
+     * @covers \PhpUnitsOfMeasure\AbstractPhysicalQuantity::isUnitDefined
+     */
+    public function testIsUnitDefined()
+    {
+    	/* The following code still doesn't work: see #63.
+		 * It is possible to enable this line (instead of the line after) to verify if #63 has been closed
+    	
+    		$newUnit = $this->getTestUnitOfMeasure('noconflict', ['definitelynoconflict_1', 'definitelynoconflict_2']);
+    	*/
+    	$newUnit = $this->getTestUnitOfMeasureSafe('noconflict', ['definitelynoconflict_1', 'definitelynoconflict_2']);
+    	Wonkicity::addUnit($newUnit);
+    	
+    	$someExistingUnits = array('u', 'uvees', 'v', 'vorp', 'noconflict', 'definitelynoconflict_1', 'definitelynoconflict_2');
+    	$unexistingUnits = array('kg', 'l', 'definitelynoconflict_');
+    	
+    	foreach ($someExistingUnits as $someExistingUnit) {
+    		$this->assertTrue(Wonkicity::isUnitDefined($someExistingUnit));
+    	}
+    	foreach ($unexistingUnits as $unexistingUnit) {
+    		$this->assertFalse(Wonkicity::isUnitDefined($unexistingUnit));
+    	}
+    }
+    
+    /**
+     * @covers \PhpUnitsOfMeasure\AbstractPhysicalQuantity::listAllUnits
+     */
+    public function testListAllUnits()
+    {
+    	/* The following code still doesn't work: see #63.
+    	 * It is possible to enable this line (instead of the line after) to verify if #63 has been closed
+    	  
+    	 $newUnit = $this->getTestUnitOfMeasure('noconflict', ['definitelynoconflict_1', 'definitelynoconflict_2']);
+    	 */
+    	$newUnit = $this->getTestUnitOfMeasureSafe('noconflict', ['definitelynoconflict_1', 'definitelynoconflict_2']);
+    	Wonkicity::addUnit($newUnit);
+    	
+    	$allUnits = Wonkicity::listAllUnits();
+    	$expected = array(
+    		'u' => array('uvee', 'uvees'),
+    		'v' => array('vorp', 'vorps'),
+    		'noconflict' => array('definitelynoconflict_1', 'definitelynoconflict_2'),
+    	);
+    	$this->assertEquals($allUnits, $expected);
+    }
+
     /**
      * Attempting to register these units should throw a DuplicateUnitNameOrAlias.
      * 1) The name of the new unit to test