diff --git a/common/internship.sty b/common/internship.sty
new file mode 100644
index 0000000..55184ff
--- /dev/null
+++ b/common/internship.sty
@@ -0,0 +1,9 @@
+\newcommand{\evec}[2]{\vec{#1}^{~#2}}
+
+\newcommand{\lsl}{\ll}
+\newcommand{\lsr}{\gg_\text{l}}
+\newcommand{\asr}{\gg_\text{a}}
+
+\newcommand{\clsl}{\ll_0}
+\newcommand{\clsr}{\gg_{0, \text{l}}}
+\newcommand{\casr}{\gg_{0, \text{a}}}