APA

Avraham, S., Tung, C., Ilic, K., Jaiswal, P., Kellogg, E., McCouch, S., Pujar, A., Reiser, L., Rhee, S., Sachs, M., Schaeffer, M., Stein, L., Stevens, P., Vincent, L., Zapata, F., & Ware, D. (2008). The Plant Ontology Database: a community resource for plant structure and developmental stages controlled vocabulary and annotations. : Oxford University Press.