adj.lacking necessary documents (as for e.g. permission to live or work in a country)

"undocumented aliens"; "undocumented tax deductions"

Health care use among undocumented Latino immigrants.
Self-selection among undocumented immigrants from Mexico
Undocumented Mexico—U.S. Migration and the Returns to Households in Rural Mexico
An analysis of public opinion toward undocumented immigration
Estimates of the Size and Characteristics of the Undocumented Population
Learning to Be Illegal: Undocumented Youth and Shifting Legal Contexts in the Transition to Adulthood
Penalized Maximal t Test for Detecting Undocumented Mean Change in Climate Data Series
Comments on ``Detection of Undocumented Changepoints: A Revision of the Two-Phase Regression Model''
Understanding the Social-Emotional Well Being of Undocumented Latino Children in the United States
China's "tidal wave"of migrant labor: what can we learn from Mexican undocumented migration to the United States?