Perhaps you should try some spelling variations:
trinh han » trinh quan
va trien » va truyen, va thiet, va tuyen
dang tay » dang xay, dan tay, bang tay
va trinh » van trinh, va tinh, lap trinh
dung tay » dung tai, vung tay, dung dat
dung may » dung va, dung tai, mang may
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ve cac » va cac, vien cac
han va » hang va, hanh va, nhan va

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 ty ((dang tay) or (((dung tay) OR (dung may)))) hoi. hieu ve cac duc va trinh han va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((dang tay) OR (((dung tay) OR (dung may)))) hoi. hieu ve cac duc va trinh han va trien*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((dang tay) or (((dung tay) OR (dung may)))) hoi. hieu ve cac duc va trinh han va trien*".