Perhaps you should try some spelling variations:
"complementary and alternative antigens" » "complementary and alternative nitrogen" (Expand Search), "complementary and alternative nutrient" (Expand Search), "complementary and alternative option" (Expand Search)
"complementary and alternative designs" » "complementary and alternative tests" (Expand Search), "complementary and alternative depictions" (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("complementary and alternative designs") OR ("complementary and alternative antigens"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"complementary and alternative designs\") OR (\"complementary and alternative antigens\"))*".
• Removing quotes may allow a broader search: (( complementary and alternative designs ) OR ( complementary and alternative antigens ))*.