diff --git a/README.md b/README.md
index 2a00aa0..8ab3b18 100644
--- a/README.md
+++ b/README.md
@@ -357,3 +357,11 @@ Plus, sometimes the function name I would like to use is already taken by PHP, l
 ## Misc information
 
 - ÁSÓ in hungarian means shovel
+
+## Credits
+
+https://www.geeksforgeeks.org/php-startswith-and-endswith-functions/ - used for S::startsWith() and S::endsWith()
+
+https://stackoverflow.com/a/173479/1806628 - used for A::isAssoc()
+
+https://www.php.net/manual/en/function.array-unique.php#116302 - used for A::uniqByKey()
diff --git a/src/A.php b/src/A.php
index a088e53..3cfd51e 100644
--- a/src/A.php
+++ b/src/A.php
@@ -19,7 +19,6 @@ public static function isArray($data): bool
     }
 
     // A::isAssoc(['a' => 12]) -> true
-    // https://stackoverflow.com/a/173479/1806628
     public static function isAssoc(array $data): bool
     {
         if (self::isEmpty($data)) {
@@ -131,7 +130,6 @@ public static function uniq(array $data): array
     }
 
     // A::uniqByKey('color', [['color' => 'red', ...], ['color' => 'red', ...]]) -> [['color => 'red', ...]]
-    // https://www.php.net/manual/en/function.array-unique.php#116302
     public static function uniqByKey($key, array $data): array
     {
         $i = 0;
@@ -204,8 +202,8 @@ public static function sortByKey(
     // A::unnest([[1, 2, 3], [3, 4, [5]]]) -> [1, 2, 3, 3, 4, [5]]
     public static function unnest($data, int $levels = 1): array
     {
-        // TODO: implementálni azt, hogy több level-re legyen jó
-        // talán elég csak annyi, hogy rekurzívan meghívjuk az unnest-et, amíg $levels-- > 0
+        // TODO: implement this to work with any $levels
+        // it might be enought just to do a recursion until --$levels === 0
         return self::reduce(
             function ($acc, $x) {
                 return self::append($x, $acc);
@@ -296,7 +294,6 @@ public static function includes($value, array $data): bool
     // A::slice(2, 4, [1, 2, 3, 4, 5]) -> [3, 4, 5]
     public static function slice(int $fromIndex, int $toIndex, array $data): array
     {
-        // TODO: make it work with negative numbers
         return array_slice($data, $fromIndex, $toIndex);
     }
 
diff --git a/src/S.php b/src/S.php
index 10dd1d1..d21b0eb 100644
--- a/src/S.php
+++ b/src/S.php
@@ -59,8 +59,6 @@ public static function includes(
     // S::split(' ', "aab bbc ccd") -> ['aab', 'bbc', 'ccd']
     public static function split(string $separator, string $data): array
     {
-        // TODO: ez nem biztos, hogy UTF-8 kompatibilis
-        // https://www.php.net/manual/en/function.mb-strtolower.php#118378
         return explode($separator, $data);
     }
 
@@ -93,7 +91,6 @@ public static function slice(int $startPos, int $endPos, string $data): string
     }
 
     // S::startsWith("ab", "abcd") -> true
-    // https://www.geeksforgeeks.org/php-startswith-and-endswith-functions/
     public static function startsWith(
         string $startString,
         string $data,
@@ -107,7 +104,6 @@ public static function startsWith(
     }
 
     // S::endsWith("ab", "abcd") -> false
-    // https://www.geeksforgeeks.org/php-startswith-and-endswith-functions/
     public static function endsWith(
         string $endString,
         string $data,