Probable place of publication:
When the place is unknown, and a good guess as to where the piece was published can be made, enclose the assumed location in square brackets with a question mark. A probable city or state, province, etc. is preferable to a probable country.
U.S. Government Publications: assume Washington, D.C.
Source: U.S. Department of Energy
260 [Washington, D.C.?] :|bU.S. Dept. of Energy
University Publications: assume the location of the university.
Source: College of Business Administration, University of Tulsa
260 [Tulsa, Okla.?] :|bCollege of Business Administration, University of Tulsa
No probable place of publication ( [S.l.] ):
When no place or probable place can be given, use "[S.l.]" (standing for "sine loco," without place). Capitalize the "S" only if occurs in the first subfield |a in the field.
260 [S.l.] :|bBlackwing Press,|c1991.
260 Philadelphia :|bPharmacopeial Convention ;|a[s.l.] :|bMack Pub. Co.,|c1980.