Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
dan cach » dan cac, dan canh, nhan cach
cach dau » sach dau, mach dau, cac dan
cao hoc » cho hoc, chat hoc
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cam tuc » cam xuc, cam tu, nam thuc
tu sach » thu sach, su sach, te sach
ve cam » ve cham, ve cac, va cam
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
co hoi » co loi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((co hoi) or (((cao hoc) OR (co hoc)))). hieu ve cam tuc va dan cach dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((co hoi) OR (((cao hoc) OR (co hoc)))). hieu ve cam tuc va dan cach dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((co hoi) or (((cao hoc) OR (co hoc)))). hieu ve cam tuc va dan cach dau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((co hoi) or (((cao hoc) OR (co hoc)))). hieu ve cam tuc va dan cach dau tren*.