diff --git a/sage/curve_family_bls12.sage b/sage/curve_family_bls12.sage
index abe9223..701c8aa 100644
--- a/sage/curve_family_bls12.sage
+++ b/sage/curve_family_bls12.sage
@@ -1,3 +1,21 @@
+# Constantine
+# Copyright (c) 2018-2019    Status Research & Development GmbH
+# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+# ############################################################
+#
+#                    BLS12 Curves parameters
+#       (Barreto-Lynn-Scott with embedding degree of 12)
+#
+# ############################################################
+#
+# This module derives a BLS12 curve parameters from
+# its base parameter u
+
 def compute_curve_characteristic(u_str):
   u = sage_eval(u_str)
   p = (u - 1)^2 * (u^4 - u^2 + 1)//3 + u
diff --git a/sage/curve_family_bn.sage b/sage/curve_family_bn.sage
index 8945793..2a2a443 100644
--- a/sage/curve_family_bn.sage
+++ b/sage/curve_family_bn.sage
@@ -1,3 +1,21 @@
+# Constantine
+# Copyright (c) 2018-2019    Status Research & Development GmbH
+# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+# ############################################################
+#
+#                    BN Curves parameters
+#                  (Barreto-Naehrig curves)
+#
+# ############################################################
+#
+# This module derives a BN curve parameters from
+# its base parameter u
+
 def compute_curve_characteristic(u_str):
   u = sage_eval(u_str)
   p = 36*u^4 + 36*u^3 + 24*u^2 + 6*u + 1
diff --git a/sage/non_residues.sage b/sage/non_residues.sage
new file mode 100644
index 0000000..7f76199
--- /dev/null
+++ b/sage/non_residues.sage
@@ -0,0 +1,68 @@
+# Constantine
+# Copyright (c) 2018-2019    Status Research & Development GmbH
+# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+# ############################################################
+#
+#             Quadratic and Cubic Non-Residue
+#
+# ############################################################
+#
+# This script checks the compatibility of a field modulus
+# with given tower extensions
+
+# ############################################################
+# 1st try
+
+# # Create the field of x ∈ [0, p-1]
+# K.<p> = NumberField(x - 1)
+#
+# # Tower Fp² with Fp[u] / (u² + 1) <=> u = 𝑖
+# L.<im> = K.extension(x^2 + 1)
+#
+# TODO how to make the following work?
+# # Tower Fp^6 with Fp²[v] / (v³ - (u + 1))
+# M.<xi> = L.extension(x^3 - (im + 1))
+
+# ############################################################
+# 2nd try
+
+# # Create the field of u ∈ [0, p-1]
+# p = Integer('0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47')
+# Fp = GF(p)
+# Elem.<u> = Fp[]
+# print("p mod 4 = ", p % 4)
+#
+# # Tower Fp² with Fp[u] / (u² + 1) <=> u = 𝑖
+# Fp2.<im> = Fp.extension(u^2 + 1)
+# Elem2.<v> = Fp2[]
+#
+# # Tower Fp^6 with Fp²[v] / (v³ - (u + 1))
+# Fp6.<xi> = Fp.extension(v^3 - (im + 1))
+# Elem6.<w> = Fp6[]
+
+# ############################################################
+# 3rd try
+# K.<xi, im, p> = NumberField([x^3 - I - 1, x^2 + 1, x - 1])
+
+# ############################################################
+# Let's at least verify Fp6
+print('Verifying non-residues')
+
+modulus = Integer('0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47')
+
+Fp.<p> = NumberField(x - 1)
+r1 = Fp(-1).residue_symbol(Fp.ideal(modulus),2)
+print('Fp² = Fp[sqrt(-1)]: ' + str(r1))
+
+Fp2.<im> = Fp.extension(x^2 + 1)
+xi = Fp2(1+im)
+r2 = xi.residue_symbol(Fp2.ideal(modulus),3)
+# ValueError: The residue symbol to that power is not defined for the number field
+# ^ AFAIK that means that Fp2 doesn't contain the 3rd root of unity
+#   so we are clear
+print('Fp6 = Fp²[cubicRoot(1+I)]: ' + str(r2))