Biotechniques. 2005 Mar;38(3):451-8.

Ohara R, Kikuno RF, Kitamura H, Ohara O.

cDNA library construction from a small amount of RNA: adaptor-ligation approach for two-round cRNA amplification using T7 and SP6 RNA polymerases.

High size is preserved by ligating a 5'adapter before each amplification.