Perhaps you should try some spelling variations:
phan thi » pham thi, tran thi, phan tu
phan tai » pham tai, nhan tai, han tai
cham cuu » cap cuu, chat cua
su sach » so sach, vu sach
ve cham » va cham, ve chat, vu cham
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu va, hieu van
cuu va » cuu van, cuu ve
thiet » thieu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang xa) OR (nang x)) hoi. hieu ve cham cuu va ((phan tai) OR (phan thi)) va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((nang xa) or (nang x)) hoi. hieu ve cham cuu va ((phan tai) OR (phan thi)) va thiet~".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang x)) hoi. hieu ve cham cuu va ((phan tai) OR (phan thi)) va thiet*.