diff --git a/trunk/todo.txt b/trunk/todo.txt
index d7558e20c..ceec8baf9 100644
--- a/trunk/todo.txt
+++ b/trunk/todo.txt
@@ -3,3 +3,11 @@ Things to be implemented into the code
 # adopt CPFEM_GIA8.f90 to new scheme, use "select case" to switch between homogenization schemes in CPFEM.f90
 # make OpenMP parallelization work again
 # adopt constitutive_dislo
+
+# check out 
+@phdthesis{Bal98,
+	Author = {Balasubramanian, Srihari},
+	School = {Massachusetts Institute of Technology},
+	Title = {Polycrystalline Plasticity: Application to Deformation Processing of Lightweight Metals},
+	Year = {1998}}
+for an analytical way to calculate the Jacobian matrix instead of the numerical perturbation technique currently employed.