sources.txt

https://stackoverflow.com/questions/5734720/test-if-object-is-instanceof-a-parameter-type
A* Algorithm: https://www.youtube.com/watch?v=-L-WgKMFuhE
https://stackoverflow.com/questions/2318020/merging-two-images
BufferedImage To GreenfootImage: https://www.greenfoot.org/topics/2032
https://stackoverflow.com/questions/12569833/generic-methods-returning-dynamic-object-types
https://www.codejava.net/java-se/file-io/how-to-read-and-write-text-file-in-java
https://www.informatikzentrale.de/greenfoot-texte-anzeigen.html
https://wiki.byte-welt.net/wiki/Flie%C3%9Fkommazahlen_mit_Java_runden

Images:
Tower Logo: https://st3.depositphotos.com/9461386/35793/v/600/depositphotos_357938824-stock-illustration-pixel-castle-games-web-sites.jpg
Bow: https://minecraft.gamepedia.com/File:Bow_JE2_BE1.png
Bomb: https://www.shutterstock.com/de/image-vector/black-bomb-pixel-art-colorful-vector-1038994675
Bullet: https://www.reddit.com/r/PixelArt/comments/dx8oyi/bullet/
Arrow1: https://static.wikia.nocookie.net/minecraft/images/4/41/Arrow.png/revision/latest/scale-to-width-down/160?cb=20200118044944
Arrow2: https://pixlr.com/stock/details/1001468162-pixel-art-arrow/
Mouse-Logo: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSxLvqIEisP-8gVDHxSUEmrW4-FTiSLwClPXg&usqp=CAU
Zombie: Zombie Entity Model (from Minecraft) by Mojang 
Land mine logo: https://img.favpng.com/24/1/2/animation-youtube-pixel-art-land-mine-png-favpng-nTKFNnqSH2dnh0Vd42GB7naP1.jpg
Slime Field Logo: https://static.wikia.nocookie.net/minecraft_gamepedia/images/d/d0/Slimeball_JE2_BE2.png/revision/latest/scale-to-width-down/150?cb=20190501035326
Coin: https://www.pngkit.com/png/full/347-3474131_coin-smiley-emoji-pixel-art.png
Path: https://sutor-coaching.de/wp-content/uploads/sites/8/2018/04/tree-3092026_640_pixabay_neue-Pfade.jpg
Dirt: https://diybook.de/sites/default/files/styles/amp_3_2/public/gartenboden_und_blumenerde_-_blumenerde.jpg?itok=-Amql0oL
Gate: https://thumbs.dreamstime.com/b/closed-metal-fence-isolated-white-background-d-rendering-i-illustration-top-view-89691058.jpg
Path: https://opengameart.org/sites/default/files/32x32GrassAndDirtPath.png

Sounds:
SniperTower_Shoot.wav: http://soundbible.com/1788-Sniper-Rifle.html
Soundfiles ArcherTower_Shoot, Bomb_Explosion, Bomb_Ignite, Zombie_Death und Zombie_Hurt: from Game Minecraft by Mojang