  We observed spectra of highly ionized tungsten in the extreme ultraviolet
with an electron beam ion trap (EBIT) and a grazing incidence spectrometer at
the National Institute of Standards and Technology. Stages of ionization were
distinguished by varying the energy of the electron beam between 2.1 keV and
4.3 keV and correlating the energies with spectral line emergence. The spectra
were calibrated by reference lines of highly ionized iron produced in the EBIT.
Identification of the observed lines was aided by collisional-radiative
modeling of the EBIT plasma. Good quantitative agreement was obtained between
the modeling results and the experimental observations. Our line
identifications complement recent results for W$^{40+}$-W$^{45+}$ observed in a
tokamak plasma by P\"{u}tterich {\it et al} (\jpb {\bf 38}, 3071, 2005). For
most lines we agree with their assignment of ionization stage. Additionally, we
present new identifications for some allowed and forbidden lines of W$^{39+}$,
W$^{44+}$, W$^{46+}$, and W$^{47+}$. The uncertainties of our wavelengths range
from 0.002 nm to 0.010 nm.
