Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
thai cua » than cua, tai cuc, tri cua
thu sach » thuat sach, thuoc sach, thu hoach
va nhanh » va thanh, va hanh, va nganh
va nhan » van nhan, ca nhan, va phan
tu sach » su sach, te sach, tu cach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cua te » cua tu

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) or (thu sach)) ky lang xa hoi. hieu vien cac nuoc ((va nhanh) OR (va nhan)) thai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky lang xa hoi. hieu vien cac nuoc ((va nhanh) OR (va nhan)) thai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ky lang xa hoi. hieu vien cac nuoc ((va nhanh) OR (va nhan)) thai cua te*".