Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
te sach » toc sach
nang va » nang van, hang va, bang va
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va thanh, va danh
tuc va » thuc va, truc va, tuc xa
vi va » vi van, vai va, vu 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: te sach thi ((nang va) OR (nang ma)) hoi. hieu va cac tuc va hanh vi va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thi ((nang va) OR (nang ma)) hoi. hieu va cac tuc va hanh vi va thiet".
• Adding a wildcard symbol may retrieve word variants: te sach thi ((nang va) OR (nang ma)) hoi. hieu va cac tuc va hanh vi va thiet*.