Towards building a first northern-sky sample of 'Extremely Inverted
  Spectrum Extragalactic Radio Sources (EISERS)'
  We present here an extension of our search for EISERS (Extremely Inverted
Spectrum Extragalactic Radio Sources) to the northern hemisphere. With an
inverted radio spectrum of slope $\alpha$ $>$ + 2.5, these rare sources would
either require a non-standard particle acceleration mechanism (in the framework
of synchrotron self-absorption hypothesis), or a severe free-free absorption
which attenuates practically all of their synchrotron radiation at metre
wavelengths. A list of 15 EISERS candidates is presented here. It was assembled
by applying a sequence of selection filters, starting with the two available
large-sky radio surveys, namely the WENSS (325 MHz) and the ADR-TGSS (150 MHz).
These surveys offer the twin advantages of being fairly deep (typical rms $<$
10 mJy/beam) and having a sub-arcminute resolution. Their zone of overlap
spreads over 1.3$\pi$ steradian in the northern hemisphere. Radio spectra are
presented for the entire sample of 15 EISERS candidates, of which 8 spectra are
of GPS type. Eleven members of the sample are associated with previously known
quasars. Information on the parsec-scale radio structure, available for several
of these sources, is also summarized.
