Perhaps you should try some spelling variations:
hoach khoi » hoach hoi, hoc khoi, hoach hoa
nghiep su » nghiep sua, nghiep vu, nghiep so
thu sach » tu sach, thuat sach, thuoc sach
sach da » sach dao, sach dat, sach dau
da nghe » day nghe, va nghe, dang nghe
du hoc » tu hoc, duoc hoc
su hoc » tu hoc, so hoc, su ho
d hoc » ad hoc, de hoc, y hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( thu sach da nghe ((d hoc) or (du hoc)) ) or ( thu hoach khoi nghiep su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thu sach da nghe ((d hoc) OR (du hoc)) ) OR ( thu hoach khoi nghiep su hoc )).
• Adding a wildcard symbol may retrieve word variants: (( thu sach da nghe ((d hoc) or (du hoc)) ) or ( thu hoach khoi nghiep su hoc ))*.