diff --git a/src/11_nearly_free_electron_model.md b/src/11_nearly_free_electron_model.md
index 4fd9cc8485d7eefc652185b48dec015cf600a025..6f8d3cde08e627258d359f0fac1f00fcd2a9d353 100644
--- a/src/11_nearly_free_electron_model.md
+++ b/src/11_nearly_free_electron_model.md
@@ -39,11 +39,11 @@ In other words: any electron wave function in a crystal is a product of a period
 
 ### Extra remarks
 
-The wave function $u_n(\mathbf{r})e^{i\mathbf{kr}}$ is called a **Bloch wave**.
+The wave function $u_n(\mathbf{r})e^{i\mathbf{k} \cdot \mathbf{r}}$ is called a **Bloch wave**.
 
 The $u_n(\mathbf{r})$ part is some unknown function. To calculate it we need to solve the Schrödinger equation. It is hard in general, but there are two limits when $U$ is "weak" and $U$ is "large" that provide us with most intuition.
 
-If we change $\mathbf{k}$ by a reciprocal lattice vector $\mathbf{k} \rightarrow \mathbf{k} + h\mathbf{b}_1 + k\mathbf{b}_2 + l\mathbf{b}_3$, and we change $u_n(\mathbf{r}) \rightarrow u_n(\mathbf{r})\exp\left[-h\mathbf{b}_1 - k\mathbf{b}_2 - l\mathbf{b}_3\right]$ (also periodic!), we obtain the same wave function. Therefore energies of all bands $E_n(\mathbf{k})$ are periodic in reciprocal space with the periodicity of the reciprocal lattice.
+If we change $\mathbf{k}$ by a reciprocal lattice vector $\mathbf{k} \rightarrow \mathbf{k} + h\mathbf{b}_1 + k\mathbf{b}_2 + l\mathbf{b}_3$, and we change $u_n(\mathbf{r}) \rightarrow u_n(\mathbf{r})\exp\left[i(-h\mathbf{b}_1 - k\mathbf{b}_2 - l\mathbf{b}_3)\cdot \mathbf{r}\right]$ (also periodic!), we obtain the same wave function. Therefore energies of all bands $E_n(\mathbf{k})$ are periodic in reciprocal space with the periodicity of the reciprocal lattice.
 
 Bloch theorem is extremely similar to the ansatz we used in [1D](7_tight_binding.md), and to the description of the [X-ray scattering](10_xray.md).