diff --git a/mapytex/calculus/core/MO/mo.py b/mapytex/calculus/core/MO/mo.py
index ad3c9a1..4902f31 100644
--- a/mapytex/calculus/core/MO/mo.py
+++ b/mapytex/calculus/core/MO/mo.py
@@ -255,6 +255,19 @@ class MOstr(MO):
     def variable(self):
         return self._variable
 
+    @property
+    def coefficients(self):
+        """ Dictionnary of coefficients
+
+        :example:
+        >>> p = MOstr("x")
+        >>> p.coefficients
+        {1: <MOnumber 1>}
+        """
+
+        return {1: MOnumber(1)}
+
+
 # -----------------------------
 # Reglages pour 'vim'
 # vim:set autoindent expandtab tabstop=4 shiftwidth=4:
diff --git a/mapytex/calculus/core/MO/monomial.py b/mapytex/calculus/core/MO/monomial.py
index d461f45..392677b 100644
--- a/mapytex/calculus/core/MO/monomial.py
+++ b/mapytex/calculus/core/MO/monomial.py
@@ -66,6 +66,19 @@ class MOstrPower(MO):
 
         MO.__init__(self, _tree)
 
+
+    @property
+    def coefficients(self):
+        """ Dictionnary of coefficients
+
+        :example:
+        >>> p = MOstrPower("x", 2)
+        >>> p.coefficients
+        {2: <MOnumber 1>}
+        """
+
+        return {self.power.value: MOnumber(1)}
+
     @property
     def variable(self):
         return self._variable
@@ -150,6 +163,18 @@ class MOMonomial(MO):
     def coefficient(self):
         return self._coefficient
 
+    @property
+    def coefficients(self):
+        """ Dictionnary of coefficients
+
+        :example:
+        >>> p = MOMonomial(3, "x", 2)
+        >>> p.coefficients
+        {2: <MOnumber 3>}
+        """
+
+        return {self.power.value: self._coefficient}
+
     @property
     def strpower(self):
         if self._power == 1: