SIMBAD references

We present relative elemental abundances for a representative sample of 53 symbiotic stars in our Galaxy. We derive the He abundances taking into account self-absorption effects in Balmer lines. Our results for N/O, Ne/O, Ar/O and He/H show that symbiotic stars follow the same trend as other well-known tracers of Galactic chemical evolution such as planetary nebulae. The increasing number of suspected symbiotic stars being discovered in X-rays and optical wavelengths suggests that symbiotic stars may play a key role in diagnostics of the Galaxy evolution in advanced stages.