Crazyhouse • Captured pieces can be dropped back on the board

Frontiers Learning to Play the Chess Variant Crazyhouse Above World Champion Level With Deep Neural Networks and Human Data

Game 2, White to move. White has three knights, a bishop, and a queen

Crazyhouse - Chess Terms

black to play and win (crazyhouse) : r/chess

Chess User Guide for Mac - Apple Support

Crazyhouse - Chess Terms

XBoard user guide

A quick survey about Shogi : r/chessvariants

Crazyhouse Chess Rules and Basics