Perhaps you should try some spelling variations:
hoc thuoc » hoc thuc, hoc thuong, hoc nuoc
lang van » dang van, tang van, hoang van
doc thuc » hoc thuc, do thuc, dan thuc
su sach » vu sach
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
hieu ve » hieu va, hieu van
van hoi » van hoa, van hoc, van hoe
ky lang » ky nang, ky dang, ky tang
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

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