S.Y. Lee, Ji Se-Wan, Lee Chang-Woo. (2013). Increasing and decreasing entanglement characteristics for continuous variables by a local photon subtraction. Phys. Rev. A87 052321
S.Y. Lee, C. Noh, D. Kaszlikowski. (2013). Identifying quantumness via addition-then-subtraction operation. Phys. Rev. A88 013806