Perhaps you should try some spelling variations:
qua tham » qua cham, qua thanh, quan pham
van hanh » van thanh, ban hanh, van anh
qua than » qua thanh, qua phan, qua tan
tu sach » thu sach, te sach, tu cach
hanh ki » hanh vi, hanh ky, hanh kien
xuc van » duc van, luc van, vuc van
su viet » so viet
tang ma » mang may, tang van
tu tang » tuc tang, tu trang, tu tong
su sach » so sach, vu sach
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) tu tang ma hoa. hieu ((qua tham) OR (qua than)) xuc van hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) tu tang ma hoa. hieu ((qua tham) OR (qua than)) xuc van hanh ki su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) tu tang ma hoa. hieu ((qua tham) OR (qua than)) xuc van hanh ki su viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) tu tang ma hoa. hieu ((qua tham) OR (qua than)) xuc van hanh ki su viet*.