[1] 日本語組版処理の要件(日本語版) ( (Japanese Layout Task Force 著, 版)) <http://www.w3.org/TR/jlreq/ja/#unbreakable_character_sequences>
[2] 日本語組版処理の要件(日本語版) ( (Japanese Layout Task Force 著, 版)) <http://www.w3.org/TR/jlreq/ja/#possibilities_for_linebreaking_between_characters>
[3] 日本語組版処理の要件(日本語版) ( (Japanese Layout Task Force 著, 版)) <http://www.w3.org/TR/jlreq/ja/#term.unbreakable-characters-rule>