α. 1700s boughou, 1700s– buchu, 1800s boego, 1800s boocho, 1800s bouchue, 1800s–1900s boekhoo, 1900s– boegoe, 1900s– bouchu, 1900s– bucho.
β. 1700s–1900s bucku, 1800s boekoe, 1800s bucca, 1800s buckhoe, 1800s bukku, 1800s–1900s bookoo, 1800s–1900s buku.
γ. 1800s boco, 1800s boka.