Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
tinh va » tich va, trinh van, trinh vat
kinh va » kinh van, sinh va, minh va
nam qua » nam quan, nam cua, nam mua
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
cuu tre » cua tre, cau tren, cau treo
ha hoi » hoa hoi, ha noi, xa hoi
qua va » quan va, qua van, vua va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((ky lang) OR (ky tang)) ha hoi. hieu van nam qua va ((kinh va) or (tinh va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((ky lang) OR (ky tang)) ha hoi. hieu van nam qua va ((kinh va) OR (tinh va)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((ky lang) OR (ky tang)) ha hoi. hieu van nam qua va ((kinh va) or (tinh va)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ((ky lang) OR (ky tang)) ha hoi. hieu van nam qua va ((kinh va) or (tinh va)) cuu tre*.