1997, Jan Małuszyński, Logic Programming: Proceedings of the 1997 International Symposium - Page 191:Consider the rules that define directly or undirectly the goal and let X be a list of a(/) distinct variables. Since /(X) is free w.r.t. X by hypothesis, it is possible to rewrite the variables in the above rules so that they are a subset of X.
2000, Alvin J. Beitz, Ph.D., John H. Anderson, Neurochemistry of the Vestibular System - Page 171:Serotonin I0-*M 20mV Serotonin IO-*M (TTX) 20mV 60s Figure 8.2 On slices, MVN neurons could be either directly or undirectly depolarized by serotonin.
2010, Catherine Rhodes, International Governance of Biotechnology:Article I details the main obligations of states parties, who undertake: Never under any circumstances: (a) To develop, produce, otherwise acquire, stockpile or retain chemical weapons, or transfer, directly or undirectly, chemical weapons to anyone ...