[C ii] (black) and CO (red; Liszt & Pety 2012) spectra at the positions CO-peak and CO-void in B0355+508 (left) and B0212+735 (right). The spectra of B0355+508 are smoothed to a velocity resolution of Δv = 0.8 km s^-1; B0212+735 spectra are smoothed to Δv = 0.4 km s^-1. The blue dashed line shows the HCO⁺ absorption spectra along the lines of sight towards the quasars B0355+508 and 0212+735 (Liszt & Lucas 1996, 2000). The red letters mark CO velocity components in the CO-peak and the CO-void, blue letters mark HCO⁺ absorption components along the line of sight towards the quasar. Identical capital letters mark related velocity components in the three positions. For better clarity we do not show the identified HCO⁺ absorption component F_Q at v_LSR = 2.5 km s^-1 in B0212+735 (cf. Table 3) reported by Lucas & Liszt (1996).