Read the passage from When Birds Get the Flu by John DiConsiglio. In 2005, a study began testing a possible bird flu vaccine on 450 people. The vaccine uses a type of bird flu that was found in Southeast Asia in 2004. Some of the early results are promising. But as of spring 2007, there is still no vaccine available for H5N1.

What would a researcher most likely consult next as a credible source for a paper on current H5N1 research?