Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
van cau » van dau, van hau, van chat
truc va » thuc vat, trung va
thuc va » thuc vat, thuc dan, thuc day
hanh va » hang va, hanh vi
dau tre » dau tren, dau tien, cau tren
va dau » va dao

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 thu nang xa hoi. hieu van cau ((truc va) or (thuc va)) hanh va dau tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang xa hoi. hieu van cau ((truc va) OR (thuc va)) hanh va dau tre.
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang xa hoi. hieu van cau ((truc va) or (thuc va)) hanh va dau tre*.