Perhaps you should try some spelling variations:
hoc viet » hoc hien
san viet » gian viet, anh viet
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
bo sach » co sach, hoc sach
hieu ve » hieu va, hieu van
ma hoi » mai hoi, xa hoi, ma hoa
ve nam » he nam, va nam, le nam

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 (bo sach)) ky sang ma hoi. hieu ve nam thuc vat hanh vi ((san viet) or (hoc viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (bo sach)) ky sang ma hoi. hieu ve nam thuc vat hanh vi ((san viet) OR (hoc viet)).
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (bo sach)) ky sang ma hoi. hieu ve nam thuc vat hanh vi ((san viet) or (hoc viet))*.