Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
van hanh » van thanh, ban hanh, van anh
tham xuc » tham nuoc, tham thuc, pham duc
qua tham » qua cham, qua than, qua thanh
tu sach » su sach, te sach, tu cach
hanh ki » hanh vi, hanh ky, hanh kien
xuc van » duc van, luc van, vuc van
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
su viet » so viet
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 (thu sach)) tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) tu ((nang ma) OR (tang ma)) hoi. hieu qua tham xuc van hanh ki su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh ki su viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh ki su viet*.