Perhaps you should try some spelling variations:
lieu vien » lieu dien, lieu viet, dieu kien
cau tren » cu tren, dau tren, ca tren
trinh do » trinh ky
tinh doi » trinh doc, tinh hoc, tinh son
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
vien cac » vien bach, vien dai, vien da
nang xa » nang x, lang xa, nang ma
sach ky » sac ky, sach ty, sach kem

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sach ky) or (sach y)) nang xa hoi. lieu vien cac nuoc va ((tinh doi) OR (trinh do)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ky) OR (sach y)) nang xa hoi. lieu vien cac nuoc va ((tinh doi) OR (trinh do)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ky) or (sach y)) nang xa hoi. lieu vien cac nuoc va ((tinh doi) OR (trinh do)) cau tren".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ky) or (sach y)) nang xa hoi. lieu vien cac nuoc va ((tinh doi) OR (trinh do)) cau tren*.