Perhaps you should try some spelling variations:
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach y, sach kem
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
hanh va » hanh vi
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat ((sach ky) or (sach ty)) nang ma hoi. hieu va cac tuc va ((hanh va) OR (hang va)) hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach ty)) nang ma hoi. hieu va cac tuc va ((hanh va) OR (hang va)) hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) or (sach ty)) nang ma hoi. hieu va cac tuc va ((hanh va) OR (hang va)) hoa viet".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) or (sach ty)) nang ma hoi. hieu va cac tuc va ((hanh va) OR (hang va)) hoa viet*.