diff --git a/os/x-ui/wm/wayland/waybar.txt b/os/x-ui/wm/wayland/waybar.txt
index 22deab4b1..2c06a3fa4 100644
--- a/os/x-ui/wm/wayland/waybar.txt
+++ b/os/x-ui/wm/wayland/waybar.txt
@@ -1,9 +1,28 @@
 https://github.com/Alexays/Waybar
+
 https://github.com/Alexays/Waybar/wiki
+https://github.com/Alexays/Waybar/wiki/Configuration
+https://github.com/Alexays/Waybar/wiki/Styling
+    https://docs.gtk.org/gtk3/css-properties.html
+    https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gtk/theme/Adwaita/_colors-public.scss
+https://github.com/Alexays/Waybar/wiki/Writing-Modules
+https://github.com/Alexays/Waybar/wiki/Module:-Hyprland
+https://github.com/Alexays/Waybar/wiki/Module:-Sway
+https://github.com/Alexays/Waybar/wiki/Module:-CPU
+https://github.com/Alexays/Waybar/wiki/Module:-Custom:-Simple
+
+https://github.com/Alexays/Waybar/tree/master/src/modules/hyprland
+https://github.com/Alexays/Waybar/tree/master/src/modules/sway
+
+https://gitlab.freedesktop.org/wlroots/wlr-protocols
+https://github.com/wmww/gtk4-layer-shell
+https://wmww.github.io/gtk-layer-shell/
 
 https://wiki.gentoo.org/wiki/Waybar
 https://wiki.hyprland.org/Useful-Utilities/Status-Bars/
 
+https://github.com/Alexays/Waybar/wiki/Examples
+
 dnf/waybar
 https://github.com/Alexays/Waybar/wiki/FAQ#how-to-use-with-sway
 https://github.com/Alexays/Waybar/wiki/Installation#how-to-use-with-sway
diff --git a/pl/java/features/stream/features/collectors.txt b/pl/java/features/stream/features/collectors.txt
index 1ae7054b0..3a34a0692 100644
--- a/pl/java/features/stream/features/collectors.txt
+++ b/pl/java/features/stream/features/collectors.txt
@@ -14,6 +14,7 @@ https://www.delftstack.com/howto/java/java-stream-distinct-by-property/
 2022
 CSC - Valeev - L9 - Terminal Operations and Collectors of 1:48:30
     https://www.youtube.com/watch?v=3qrNlWkJ3ac
+    ! 50:00 - groupingBy, mapping, flatMapping
 2021
 Tsymbalyuk - Collectors Class 0:00 of 32:27
     https://www.youtube.com/watch?v=HOQpQWK9u28
diff --git a/pl/java/features/stream/streams.txt b/pl/java/features/stream/streams.txt
index 83d75a697..cfc075d28 100644
--- a/pl/java/features/stream/streams.txt
+++ b/pl/java/features/stream/streams.txt
@@ -39,6 +39,9 @@ characterized by Spliterator
         - uses more memory
         - short-circuiting (find result earlier than finishing consuming all the input)
         - .flatMap...spliterator().tryAdvance() - throws OOM because of the buffering
+    https://www.youtube.com/watch?v=3qrNlWkJ3ac
+    ! 25:14
+    List<String> result = List.of(List.of("foo", "bar"), List.of("baz", "...")).flatMap(List::stream).toList()
 
 .orElseThrow(IllegalStateException::new)