Two important factors for understanding the physical nature of compact steep spectrum (CSS) radio sources are determining the correct radio morphological classification of these objects together with their characteristics in wavebands different from the radio (Fanti et al. 1995, A&A, 302, 317). Seven CSS sources (linear dimensions < 30kpc for Ho = 50 kms–1Mpc–1 and α > 0.5, S ≃ v –α) have been found in a complete sample of strong southern radio sources. This group of CSS sources is particularly interesting because some optical and X-ray information is already available as part of a more general study of southern radio sources (Morganti et al. & Siebert et al. these Proceedings). The spectra of all the sources were presented in Tadhunter et al. (1993, MNRAS, 263, 999.) Here we present VLBI observations for three of these sources (0252-71, 1306-09 and 1814-63). The remaining four have already been imaged with VLBI (King et al. these Proceedings).