Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, nang cai
lang mai » lang dai, lang hai, lang man
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
va cham » va chat, va tham
xuc va » tuc va, luc va, xac va
vai va » mai va, dai va, hai 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 ky ((nang mai) OR (lang mai)) hoi. hieu va cham ((xuc va) or (duc va)) hanh vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang mai) OR (lang mai)) hoi. hieu va cham ((xuc va) OR (duc va)) hanh vai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang mai) OR (lang mai)) hoi. hieu va cham ((xuc va) or (duc va)) hanh vai va thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang mai) OR (lang mai)) hoi. hieu va cham ((xuc va) or (duc va)) hanh vai va thiet*.