| "Soundtrim Modulating Low Noise Control Plug Valve", Durco Brochure Bulletin V-37, Jun., 1987. |
| NAF-Trimball (undated). |
| "Series 61 and 62 High Performance Rotary Valve", Introl, undated. |
| "Anticavitation Rotary Control Valve, Rotrol-Series 61", InTech, Sep., 1987. |
| Neles Q-Ball.RTM., "Trim Alternatives", May, 1986. |
| Neles, "Control Valves for Gas Transmission and Distribution", Application Data Sheet 5B1, Oct., 1986. |
| Neles, "Control Valves Series R11 and Q-R11", Jan., 1988. |
| Neles-Jamesbury, "Q-Ball.RTM. Quiet Metal Seated Rotary Control Valve", Mar., 1989. |
| Neles, "Q-Ball.RTM. Valve Applications for Power Plants", Application Data Sheet-7B1, undated. |