Perhaps you should try some spelling variations:
hoc viet » hoc hien
van hanh » van thanh, ban hanh, van anh
tuc van » thuc van, truc van, tuc va
vu sach » vu bach, su sach, vu khach
may hoi » may thoi, tay hoi, mai hoi
ty hang » ly hang, thi hang, thu hang
va cam » va cham, va cac, va cao
vi hoc » li hoc, va hoc
ve cam » ve cham, ve cac, ve cai

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 ((ty hang) OR (ty xang)) may hoi. hieu ((ve cam) or (va cam)) tuc van hanh vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ((ty hang) OR (ty xang)) may hoi. hieu ((ve cam) OR (va cam)) tuc van hanh vi hoc viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ((ty hang) OR (ty xang)) may hoi. hieu ((ve cam) or (va cam)) tuc van hanh vi hoc viet".
• Adding a wildcard symbol may retrieve word variants: vu sach ((ty hang) OR (ty xang)) may hoi. hieu ((ve cam) or (va cam)) tuc van hanh vi hoc viet*.