^For the difference between bunkers and blockhouses see Schneider & Kitchen 2002,第87页 harvnb模板错误: 无指向目标: CITEREFSchneiderKitchen2002 (帮助), BACM Research 2009,第263页 harvnb模板错误: 无指向目标: CITEREFBACM_Research2009 (帮助), Davis 2007,第290页 harvnb模板错误: 无指向目标: CITEREFDavis2007 (帮助)