diff --git a/gtsam/mainpage.dox b/gtsam/mainpage.dox
index db42b1277..59e7f9fa6 100644
--- a/gtsam/mainpage.dox
+++ b/gtsam/mainpage.dox
@@ -17,11 +17,11 @@ To use GTSAM to solve your own problems, you will often have to create new facto
 
 -# The number of variables your factor involves is <b>unknown</b> at compile time - derive from NoiseModelFactor and implement NoiseModelFactor::unwhitenedError()
    - This is a factor expressing the sum-of-squares error between a measurement \f$ z \f$ and a measurement prediction function \f$ h(x) \f$, on which the errors are expected to follow some distribution specified by a noise model (see noiseModel).
--# The number of variables your factor involves is <b>known</b> at compile time and is between 1 and 6 - derive from NonlinearFactor1, NonlinearFactor2, NonlinearFactor3, NonlinearFactor4, NonlinearFactor5, or NonlinearFactor6, and implement <b>\c evaluateError()</b>
+-# The number of variables your factor involves is <b>known</b> at compile time and is between 1 and 6 - derive from NoiseModelFactor1, NoiseModelFactor2, NoiseModelFactor3, NoiseModelFactor4, NoiseModelFactor5, or NoiseModelFactor6, and implement <b>\c evaluateError()</b>
    - This factor expresses the same sum-of-squares error with a noise model, but makes the implementation task slightly easier than with %NoiseModelFactor.
 -# Derive from NonlinearFactor
    - This is more advanced and allows creating factors without an explicit noise model, or that linearize to HessianFactor instead of JacobianFactor.
 
 */
 
-}
\ No newline at end of file
+}