Perhaps you should try some spelling variations:
tham nhung » thi nhung
tham cung » thay cung, pham cong, tho cung
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
hanh ki » hanh vi, hanh ky, hanh kien
hieu va » lieu va, hieu qua
nang xa » lang xa, nang ma, mang xa
su viet » so viet
sach v » sach va, sach y, sach 2
ki su » ky su

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 v ((nang xa) or (nang x)) hoi. hieu va ((tham cung) OR (tham nhung)) van hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang xa) OR (nang x)) hoi. hieu va ((tham cung) OR (tham nhung)) van hanh ki su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((nang xa) or (nang x)) hoi. hieu va ((tham cung) OR (tham nhung)) van hanh ki su viet".
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang xa) or (nang x)) hoi. hieu va ((tham cung) OR (tham nhung)) van hanh ki su viet*.