[1]
Rooijakkers, W., Kuik, G.J., Vassen, W. and Hogervorst, W. 1997. Laser cooling and trapping of metastable helium atoms. Proceedings of the Samahang Pisika ng Pilipinas, 15(1), SPP-1997-OP-11. URL: https://proceedings.spp-online.org/article/view/SPP-1997-OP-11.