Update java-collection-libs.md

docs/wiki/Lang-Java/java-collection-libs.md

@@ -10,21 +10,21 @@ tags:
 ## Overview
 
 - *Popular*
-  - [**Java Collections Framework**](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/package-summary.html)
-  - [**Apache Commons Collections**](https://github.com/apache/commons-collections)
-  - [**Guava**](https://github.com/google/guava)  is a set of core Java libraries from Google that includes new collection types (such as multimap and multiset), immutable collections, a graph library, and utilities for concurrency, I/O, hashing, primitives, strings, and more! It is widely used on most Java projects within Google, and widely used by many other companies as well.
-  - [**Eclipse Collections**](https://github.com/eclipse/eclipse-collections)
-  - [**fastutil**](https://fastutil.di.unimi.it) extends the Java Collections Framework by providing type-specific maps, sets, lists, and queues with a small memory footprint and fast access and insertion; it provides also big (64-bit) arrays, sets, and lists, sorting algorithms, fast, practical I/O classes for binary and text files, and facilities for memory mapping large files.
-  - [**JCTools**](https://github.com/JCTools/JCTools) Java Concurrency Tools for the JVM. This project aims to offer some concurrent data structures currently missing from the JDK.
+  - [Java Collections Framework](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/package-summary.html)
+  - [Apache Commons Collections](https://github.com/apache/commons-collections)
+  - [Guava](https://github.com/google/guava) [^1]
+  - [Eclipse Collections](https://github.com/eclipse/eclipse-collections)
+  - [fastutil](https://fastutil.di.unimi.it) [^2]
+  - [JCTools](https://github.com/JCTools/JCTools) [^3]
 - *Graph*
-  - [**JGraphT**](https://github.com/jgrapht/jgrapht) is Java class library that provides mathematical graph-theory objects and algorithms
-  - [**JUNG**](https://github.com/jrtom/jung) is the Java Universal Network/Graph Framework
+  - [JGraphT](https://github.com/jgrapht/jgrapht) [^4]
+  - [JUNG](https://github.com/jrtom/jung) [^5]
 - *Persistent collections*
-  - [**vavr**](https://github.com/vavr-io/vavr) provides persistent collections, functional abstractions for error handling, concurrent programming, pattern matching and much more
-- *Personal*
-  - [**kevin-wayne/algs4**](https://github.com/kevin-wayne/algs4/) is a repo for "Algorithms" 4th edition book's code and libraries
-  - [**java-algorithms-implementation**](https://github.com/phishman3579/java-algorithms-implementation) sample algorithms and data structures implemented in Java
-  - [**williamfiset/Algorithms**](https://github.com/williamfiset/Algorithms) is a collection of algorithms and data structures
+  - [vavr](https://github.com/vavr-io/vavr) [^6]
+- *Personal repos*
+  - [**kevin-wayne/algs4**](https://github.com/kevin-wayne/algs4/) *"Algorithms" 4th edition book's code and libraries*
+  - [**java-algorithms-implementation**](https://github.com/phishman3579/java-algorithms-implementation) *sample algorithms and data structures implemented*
+  - [**williamfiset/Algorithms**](https://github.com/williamfiset/Algorithms) *is a collection of algorithms and data structures*
 
 ## Java Collections Framework
 
@@ -43,4 +43,11 @@ Name | Description |
 `EnumMap` | A map in which the keys belong to an enumerated type
 `LinkedHashMap` | A map that remembers the order in which entries were added
 `WeakHashMap` | A map with values that can be reclaimed by the garbage collector if they are not used elsewhere
-`IdentityHashMap` | A map with keys that are compared by ==, not equals
+`IdentityHashMap` | A map with keys that are compared by ==, not equals
+
+[^1]: **Guava** is a set of core Java libraries from Google that includes new collection types (such as multimap and multiset), immutable collections, a graph library, and utilities for concurrency, I/O, hashing, primitives, strings, and more! It is widely used on most Java projects within Google, and widely used by many other companies as well.
+[^2]: **fastutil** extends the Java Collections Framework by providing type-specific maps, sets, lists, and queues with a small memory footprint and fast access and insertion; it provides also big (64-bit) arrays, sets, and lists, sorting algorithms, fast, practical I/O classes for binary and text files, and facilities for memory mapping large files.
+[^3]: **JCTools** Java Concurrency Tools for the JVM. This project aims to offer some concurrent data structures currently missing from the JDK.
+[^4]: **JGraphT** is Java class library that provides mathematical graph-theory objects and algorithms.
+[^5]: **JUNG** is the Java Universal Network/Graph Framework.
+[^6]: **vavr** provides persistent collections, functional abstractions for error handling, concurrent programming, pattern matching and much more.