Levine, P. B., & Staiger, D. (2001). Abortion as insurance. National Bureau of Economic Research.
Lua i Stíl Chicago (17ú heag.)Levine, Phillip B., agus Douglas Staiger. Abortion as Insurance. Cambridge: National Bureau of Economic Research, 2001.
Lua MLA (9ú heag.)Levine, Phillip B., agus Douglas Staiger. Abortion as Insurance. National Bureau of Economic Research, 2001.
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