Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thu sach » thuat sach, thuoc sach, thu hoach
vien cac » vien bach, vien dai, vien da
van dinh » van minh, van dich, va dinh
tu sach » su sach, te sach, tu cach
nang xa » nang x, lang xa, nang ma
vai cua » hai cua, lai cua, bai cua
cac bo » bac bo, cac co
bo van » vo van, so van, do van

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 nang xa hoi. hieu vien cac bo van dinh ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang xa hoi. hieu vien cac bo van dinh ((vai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky nang xa hoi. hieu vien cac bo van dinh ((vai cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ky nang xa hoi. hieu vien cac bo van dinh ((vai cua) or (dai cua)) tre*.