[栋梁 / 棟樑, dòng liángㄉㄨㄥˋ ㄌㄧㄤˊ] ridgepole; ridgepole and beams; person able to bear heavy responsibility; mainstay (of organization); pillar (of state)#37726
[汗牛充栋 / 汗牛充棟, hàn niú chōng dòngㄏㄢˋ ㄋㄧㄡˊ ㄔㄨㄥ ㄉㄨㄥˋ] lit. enough books to make a pack-ox sweat or to fill a house to the rafters (成语 saw); fig. many books#95529