Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
thuc gia » thuc giai, thue gia, thuc dia
tu sach » su sach, te sach, tu cach
ty nang » ky nang, ty xang, ty hang
dan cua » dan ca, ban cua, day cua
x hoi » xa hoi, o hoi, x ho

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) or (thu sach)) ty nang x hoi. hieu van nam thuc gia thanh ((dan cua) OR (dai cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang x hoi. hieu van nam thuc gia thanh ((dan cua) OR (dai cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty nang x hoi. hieu van nam thuc gia thanh ((dan cua) OR (dai cua)) te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty nang x hoi. hieu van nam thuc gia thanh ((dan cua) OR (dai cua)) te*.