Orthogonal design

Zheng L-L, Wang D, Li Y-Y, Peng H-Y, Yuan M-Y, Gao F. Ultrasound-assisted extraction of total flavonoids from Aconitum gymnandrum. Pharmacognosy Magazine [Internet]. 2014;10(37s):s141-s146. https://www.ncbi.nlm.nih.gov/pubmed/24914295