Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
nhan mai » nhan tai, nhan dai, nhan ma
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
xac va » tac va, ac va, bac va
tuc va » thuc va, truc va, tuc xa
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 ty nang xa hoi. hieu van tham ((((xac va) or (tuc va))) or (duc va)) nhan mai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang xa hoi. hieu van tham ((((xac va) OR (tuc va))) OR (duc va)) nhan mai va thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang xa hoi. hieu van tham ((((xac va) or (tuc va))) or (duc va)) nhan mai va thiet*.