Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
luc van » luoc van, luu van, duc van
te sach » toc sach
tac hoi » tao hoi, tay hoi, tac hai
ky danh » ky anh, ky dang
ky canh » ky anh, ky cach, ky hanh
va cam » va cham, va cac, va cai
va cao » va cac, va co, va dao
di cau » da cau, diem cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ky canh) OR (ky danh)) tac hoi. lieu ((va cam) or (va cao)) luc van hanh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky canh) OR (ky danh)) tac hoi. lieu ((va cam) OR (va cao)) luc van hanh di cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ky canh) OR (ky danh)) tac hoi. lieu ((va cam) or (va cao)) luc van hanh di cau tren".
• Adding a wildcard symbol may retrieve word variants: te sach ((ky canh) OR (ky danh)) tac hoi. lieu ((va cam) or (va cao)) luc van hanh di cau tren*.