Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
va cham » va chat, va tham
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
xuc va » tuc va, luc va, xac va
vai va » mai va, dai va, lai va
hai va » hai van, thai va, hoi va
thiet » thieu

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 y nang ma hoi. hieu va cham ((xuc va) OR (duc va)) hanh ((vai va) or (hai va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ma hoi. hieu va cham ((xuc va) OR (duc va)) hanh ((vai va) OR (hai va)) thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ma hoi. hieu va cham ((xuc va) OR (duc va)) hanh ((vai va) or (hai va)) thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ma hoi. hieu va cham ((xuc va) OR (duc va)) hanh ((vai va) or (hai va)) thiet*.