Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
hieu lang » chieu sang, hieu quang, nhieu tang
hanh tung » thanh tung, manh tung, hanh dung
dong cong » duong cong, dung cong, dang cong
tung dan » dung dan, huong dan, trung dai
dan dong » van dong, dan dung, dao dong
van toan » van tuan, van tan, van thanh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu manh) or (hieu lang)) - hanh tung dan dong cong ((xuan toan) or (van toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu manh) OR (hieu lang)) - hanh tung dan dong cong ((xuan toan) OR (van toan)) cau.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu manh) or (hieu lang)) - hanh tung dan dong cong ((xuan toan) or (van toan)) cau*.