Virtual-environment.md

@@ -59,7 +59,7 @@ While we have already seen that some tools can write their own files indicating
 
 - `requirements.txt` is a file for describing dependencies, and can be used with all the tools listed above.
 - `environment.yml` is used by tools based on `conda` packages.
-It also allows to choose the python version and the channels you want to fetch your depencies.
+It also allows to choose the python version and the channels you want to fetch your dependencies.
 
 ### `requirements.txt` example
 
@@ -72,7 +72,7 @@ jupyterlab
 requests[security]
 ```
 
-With version specifier and environment marker, you can be more precise.
+With [version specifier](https://packaging.python.org/en/latest/specifications/version-specifiers/#id5) and environment marker, you can be more precise.
 
 ```txt
 numpy>1.20
@@ -83,6 +83,8 @@ requests [security] >= 2.8.1, == 2.8.* ; python_version < "2.7"
 
 ### `environment.yml` example
 
+See more information on requirements specifiers on https://pip.pypa.io/en/stable/reference/requirement-specifiers/
+
 Without version specifier
 
 ```yaml